Globally an estimated 15% to 20% of all births are low birth weight, representing more than 20 million births a year. Low birth weights are at a greater risk of both short and long-term sequels. Therefore, this study was conducted to assess determinants and perinatal outcomes of low birth weight newborns delivered in Hawassa University Comprehensive Specialized Hospital, Southern Ethiopia.A total of 420 mothers were included in the study with a response rate of 97%. The mean birth weights of the neonate were 3360 (± 870 SD) grams and the incidence of low birth weight was found to be 16.6% (95% CI 13.46–18.38). Previous abortion [RR = 1.87 ], hypertensive disorder [RR = 4.59 ], having < 4 antenatal visits [RR = 3.45 ] and prematurity [RR = 18.2 ] was increased the risk of low birth weight. Low birth weight neonates were associated with a low Apgar score [RR = 18.2 ] and early neonatal death [RR = 18.2 ]. For this, identifying populations at the greatest risk of previous abortion, hypertensive disorders of pregnancy and prematurity were the major priorities aimed at reducing low birth weight. Incorporate mental health in the prenatal visit, improving the care for a high-risk pregnant woman was also recommended.The online version of this article (10.1186/s13104-019-4155-x) contains supplementary material, which is available to authorized users. According to the World Health Organization (WHO), low birth weight is defined as a weight of less than 2500 g (5.5 lb) at birth. Low birth weight also includes preterm neonates, small for gestational age neonates at term and the combination of these two situations, who particularly have the worst perinatal outcomes . GloballThe mother’s own fetal growth and her diet during adolescent and her body composition at conception are commonly associated with low birth weight. Other risk factors for low birth weight includes multiple gestations, previous abortion, young women, socio-economic status, infections, maternal nutrition and lifestyle, and medical disorders during pregnancy including hypertensive disorders, fetal infection, and anomalies and placental pathologic conditions –5.Low birth weight is related to a range of both short and long-term sequels such as prematurity. Each year, about 1.1 million babies die from complications of prematurity. Low birth weight neonates have a > 20 times greater risk of dying than neonates with birth weight of > 2500 g , 7. ThosCurrently, WHO and other organizations are working against reducing low birth weight by 30% by the year 2025 . DespiteA hospital-based retrospective cohort study design was conducted in Hawassa University Comprehensive Specialized Hospital (HUCSH) from July 10 to August 15, 2018. The hospital is found at Hawassa City, capital of Southern Nations Nationalities and People’s Region (SNNPR), which is 275 km far from the capital city of the country, Addis Ababa. HUCSH is one of the largest Hospital in the region, which serve as a specialized and teaching hospital at the regional level and provides both delivery and neonatal intensive care unit service. The hospital serves for more than 3 million populations for the region and two zones of Oromia region.All women who delivered in the hospital in the last 1 year were the source populations. There are 4056 women who gave birth in 1 year. Exposed groups were those newborns who had low birth weight (LBW) (< 2500 g) and non exposed or normal birth weight (NBW) was that newborn who weights greater than or equals to 2500 g and those delivered in the hospital on the same day as enrolled regardless of the mode of delivery and fetal outcome. All women who gave singleton after 28 weeks of gestation or weight of at least 1000 g were included. However, mothers with congenital anomalies like  and multiple pregnancies and incomplete data were excluded. LBW and NBW were selected after reviewing of women’s chart, delivery, and neonatal logbook.and making the final sample size of 434 (73 exposed and 361 unexposed). Exposed groups were selected using random sampling technique. For each exposed, five consecutive nonexposed newborns delivered in the hospital as soon as the exposed diagnosed on the same day in the same as of exposed will be selected as a control group.The sample size was determined using double population proportion formula using Open Epi version 3 software, using the following statistical assumptions, 80% power of the study, 95% confidence interval, case to control a ratio of 1 to 5 (r = 5) and considering prematurity and abruption as predictors of low birth weight and prevalence of stillbirth 1% among non exposed group with an odds ratio of 9 from a cohort study in Zambia  and makiData were collected using structured and pre-tested questionnaire. The questionnaires were adapted from Ethiopian demographic health survey and other related literature –13. ThenThe data were coded, cleared and entered on Epi data 3.1 software and exported to Statistical package for social science (SPSS) software version 20 for analysis. Summary statistics such as mean and standard deviation and the proportion of the characteristics of LBW and NBW was computed using Chi square. Multivariable logistic regression was carried out to examine the association of the outcome variables with selected determinant factors. Variables that will be associated in bivariate logistic regression with the significance level of p-value < 0.25 entered into a multivariable logistic regression model to control possible confounding effects. Model was fitted  using Hosmer and Lemeshow fit statistic. Variables with a p value < 0.05 will be considered as statistically significant factors and odds ratio with 95% confidence interval was used to measure the strength of association. The analysis was done by reporting guidelines of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement checklist .IRB/163/10. Then permission letter was taken from the Department of midwifery and Medical clinical director. A brief explanation was given on the objectives as well as the benefit of the study to the concerned officials. Confidentiality and privacy of every patient’s information were ensured.Ethical clearance was obtained from Hawassa University, College of Medicine and Health Science, Institutional Review Board Ethical review committee with a Ref. No A total of 420 singleton births were included in this analysis with a response rate of 97%. The mean age the participant was 26.9 (± 5.5 SD) years and the birth weight was 3.36 kg (± 0.87). Seventy women had given a low birth weight (LBW) newborn, this constitutes an incidence of 16.6% (95% CI 13.46–18.38). Of those women who had LBW, 41 (58.6%) were in the age group of 20–34 years and above one third (68%) resides outside Hawassa. Mothers with LBW infants were more likely to be multigravida (61%), had a complication in the previous pregnancy (48.8%) and recent pregnancy (65.7%). Hypertensive disorder of pregnancy (37.1%) and antepartum hemorrhage (22.9%) were common among mothers gave birth with LBW newborn. Similarly, 33% of women with LBW had Antenatal care (ANC) visit; of that 60.4% had ANC visits < 4 times. Significant proportions (72.9%) of LBW were born preterm and nearly two-thirds (64.6%) of normal birth weight (NBW) newborns were male  of the LBW neonates and nearly half (48%) of the NBW neonates had at least one adverse perinatal outcomes. LBW newborns were at the higher risk of Low Apgar score (42%), early neonatal death 19.3%) and NICU admission (22.6%). LBW neonates were two times more likely at risk of low Apgar score [RR = 2.29 ] than the NBW group. The risk of early neonatal death was three times [RR = 3.02 ] more likely among the LBW newborns than the NBW neonates  on perinatal outcomes should be addressed.Despite it was a cohort study and extensive efforts have been made, the finding could be interpreted in the presence of some inevitable limitations. The study might underestimate early neonatal death due unable to assess outcome after NICU admission and death after discharge and its retrospective nature might prevent some variables, as educational level, Iron-folic acid supplementation, maternal mental health and dietary pattern of women.Additional file 1. English version Questionnaire of determinants and outcomes of low birth weight in HUCSH, Southern Ethiopia, 2018.


Antenatal depression is a significant health problem in low and middle- income countries. Although the condition is associated with severe adverse consequences for the mother and newborn, it remains a neglected problem. The purpose of this study was to describe the association between antenatal depressive symptoms and preterm birth (PTB), low birth weight (LBW), and small for gestation age (SGA).The study was conducted in Dong Anh District, Hanoi, Vietnam, among pregnant women of less than 24 weeks of gestation. Information on socioeconomic characteristics and reproductive history was collected at enrollment and ADS and experiences of intimate partner violence were assessed at week 32. Birth outcomes were determined at delivery. Bivariate and logistic regression analyses were applied to assess the associations between ADS and PTB, LBW, and SGA.ADS was significantly associated with an increased risk of PTB  and a significantly increased risk for giving birth to an LBW infant . In contrast, ADS was not statistically associated with small for gestation age.ADS is associated with an increased risk of PTB and LBW but not associated with SGA. Preterm birth (PTB), low birth weight (LBW), and small for gestation age (SGA) are the leading causes of neonatal and infant morbidity and mortality worldwide . AlthougPTB is defined as birth before 37 weeks of gestation . GloballLBW is defined as birth weight under 2500 grams and it is estimated that more than 20 million infants worldwide are LBW, accounting for 15.5% of all births . The occSGA is defined as a newborn whose weight and size at birth fall below the tenth percentile of appropriate weight for gestational age infants, whether delivered at term, or earlier or later than term . It is eDepression is a common mental disorder among pregnant women, characterized by sadness, loss of interest or pleasure, feelings of guilt or low self-worth, disturbed sleep or appetite, feelings of tiredness, and poor concentration . The preIn Vietnam, there is only one study describing the association between mental disorders, socio-demographic background factors, and PTB and LBW , whereasThis study was conducted among pregnant women attending antenatal care in Dong Anh district, a semi-urban area in Hanoi, Vietnam. The district is located 15 kilometers north-west of Hanoi. Dong Anh District has a population of about 328000 inhabitants. The average GDP per capita is about 2000 US$/year (in 2014). The area is characterized by industrial zones  mixed with agricultural zones. The district includes 23 communes and one small township. The health care services in the district are provided by two district hospitals of Dong Anh and North Thang Long and 24 commune health stations. Each hospital includes Department of Obstetrics and Gynecology with 7–10 doctors and 15–20 midwives and nurses. Each commune health station employs 6–7 health staff, including one medical physician, 3–4 nurses, one midwife, and one population collaborator. The pregnant women were recruited from all 24 communes of the district between June 2014 and July 2015.th gestational week. Estimation of gestational weeks at enrollment was based on ultrasound scanning at two district hospitals. Assessment of ADS was done at a gestational age of 30–34 weeks and data on gestational age at delivery and birth weight were collected within 48 hours after delivery. During the period June 2014 to July 2015, a total of 1337 pregnant women were recruited for the study; 1285 (96.1%) participated in the 2nd interview and delivery information was collected among 1276 (95.4%). There were no significant differences in characteristics between women who were followed throughout the study and women who were lost for follow up  ,20. The Data were collected by six local commune population staff and supervised by a research team from Hanoi Medical University. Data quality was ensured through careful training of interviewers and continuous supervision of data collection. Training of interviewers was conducted for three days, including two days for questionnaire training at Hanoi Medical University and one day pre-test training in the field. During the data collection period, six interviewers were regularly supervised by staff from Hanoi Medical University. At the end of each day of data collection, supervisors checked the quality of questionnaires in order to identify missing data and incomplete answers, and asked interviewers for completion, if needed.The outcome variables used in the present study included PTB, LBW, and SGA. PTB was defined as babies born before 37 weeks of gestation and LBW was classified according to the World Health Organization definition as newborn babies with a birth weight of less than 2500g . SGA wasADS was measured by the EPDS with 10 self-reported questions . This scBMI was defined as the woman's weight in kilograms divided by the square of height in meters and women with a BMI below 18.5 were defined as underweight . Anemia Data were managed and analyzed using SPSS software version 21.0). Descriptive analysis was used to estimate means and proportions. The prevalence of ADS and incidence rates of PTB, LBW, and SGA were calculated. Bivariate analysis and logistic regression analysis of associations between ADS and PTB, LBW, and SGA were conducted. Two logistic regressions were performed. In Model 1 the association between ADS and PTB, LBW, and SGA was adjusted for a priori potential confounders  aThe women were informed in detail about the study and written informed consent was obtained. The study proposal was submitted to and approved by the IRB:  of Hanoi Medical University. Pregnant women with depression were counselled to get professional support at medical agencies.The associations between ADS and PTB, SGA, and LBW are presented in There was no association between ADS and SGA in neither Model 1  nor Model 2 .We found a strong relationship between ADS and giving birth to a child with LBW. After adjusting for a priori potential confounders (Model 1), women with depression during pregnancy had more than three times increased OR for giving birth to an LBW infant . A similarly increased OR was found in Model 2, where all factors that were significant in the crude analysis were adjusted for .In our study, the prevalence of depression during pregnancy was 4.9%. A systematic review has shown that approximately 10% of pregnant women and 13% of those who have given birth 26] have have26] The association between ADS and the health effects of mothers and children has been given increasing attention worldwide. ADS influences the regulation of the hypothalamic-pituitary-adrenocortical axis, stimulating the release of stress hormones, such as cortisol and catecholamine. These biological changes may result in placental hypo fusion and consequent restriction of oxygen and nutrients to the fetus, leading to PTB, LBW, and SGA . ADS is We found a strong association between ADS and PTB and the association remained significant after adjusting for potential a priori confounders Model1) as well as when adjusting for factors that were significant in the crude analysis (Model 2). Many maternal factors are associated with an increased risk of PTB, including being young or of advanced maternal age, short inter-pregnancy intervals, and low maternal BMI ,32, Comm as well In our study, ADS was an important predictor of LBW. Our finding is consistent with findings from other studies. A meta-analysis in 2010 also found a stronger association between ADS and LBW in low- and middle-income countries  as compared to the United States  and Europe  . BrittaiWe found no significant association between ADS and SGA. In literature, the relationship between these variables are controversial. Findings in studies in Denmark  and the The strength of our study is that it includes a large number of pregnant women, which allowed us to analyze the association between ADS and PTB, LBW, and SGA. Moreover, the prospective cohort study design helped us to collect concise/precise and reliable data. We adjusted for the effect of both a priori potential confounders (Model 1) as well as variables with significant crude ORs (Model 2) and the results from the two models were in accordance. However, the etiology of PTB, LBW, and SGA is multifactorial and there may still be a risk of residual confounding.This study has some limitations including an absence of the use of antidepressant medications during pregnancy and lack of information on a number of non-communicable diseases such as, for example, preeclampsia, hypertension and gestational diabetes as well as HIV infection. Further, some health behaviors, such as alcohol consumption and smoking, were not included in the analysis due to the small number of enrolled women who reported such lifestyle habits. These factors have been researched by a number of studies describing predictors of PTB, LBW, and SGA around the world and positive associations have been described ,46. It mPTB, LBW, and SGA are prevalent in Vietnam. ADS is associated with an increased risk of PTB and LBW whereas no association was found in relation to SGA. Screening for ADS and implementation of appropriate interventions aimed at ADS may help improve birth outcomes. There is a need for further research to assess the association of ADS and SGA.S1 File(DOC)Click here for additional data file.S2 File(DOC)Click here for additional data file.S3 File(DOC)Click here for additional data file.S1 Dataset(XLSX)Click here for additional data file.S2 Dataset(XLSX)Click here for additional data file.


Congenital anomalies (CA) are a major cause of neonatal morbidity and mortality, especially in developing countries. Data on these anomalies are still poorly collated in developing countries. We aimed to assess the prevalence, pattern, risk factors and outcome of congenital anomalies among neonatal admissions in Ogbomoso Town, Nigeria.A cross-sectional retrospective study in which a review of the records of all neonates admitted in the neonatal unit of the Bowen University Teaching Hospital, Ogbomoso over a five-year period (January 2012–December 2016) was undertaken. The occurrence rate and pattern of anomalies were determined, while factors associated with the occurrence and outcome of anomalies were calculated with the odds ratio and 95% confidence interval. Data entry and analysis were performed using SPSS version 21.CA were found in 67 of the 1057 neonatal admissions, giving a prevalence rate of 6.3%. Anomalies of the cardiovascular and digestive systems were the most common. A higher proportion of babies referred from other facilities had CA, and this was found statistically significant. There was no significant association between CA and low birth weight, sex, maternal age or parity. The mortality rate among neonates with CA was 10.4%. Although, CA was associated with reduced risk of neonatal mortality compared to those with other acute conditions, this was not statistically significantly.CA is a major indication for neonatal admissions in Ogbomoso. There is the need to establish a surveillance system for CA and efforts should be made to raise awareness of the occurrence and risk factors of CA in developing countries.The online version of this article (10.1186/s12887-019-1471-1) contains supplementary material, which is available to authorized users. Congenital anomalies (CA), or birth defects, are structural, behavioural, functional and metabolic disorders that occur during intrauterine life and can be identified prenatally, at birth or later in infancy , 2. WhilMajor CAs are defined as anomalies with significant effect on life expectancy and they occur in 2–3% of live births and in 20–30% of still births , 7. TheiAll organ systems within the body can be affected by CA. The musculoskeletal system is the most often affected system in studies that have focused on externally visible anomalies , 14, 15.Understanding the aetiology of CA is important in prevention and in genetic counselling that may help in eradication. Generally, the aetiology of birth defects remains unclear but is thought to be multifactorial. These factors may be genetic 10–30%), environmental (5–10%) or due to multifactorial inheritance (20–35%), while 30–45% are unknown . Infecti0–30%, enMortality is very high among major CA in LMICs rising to 20–85% (as against less than 10% in high-income countries) and generally, mortality is higher among infants with CA compared to normal births , 22–24. Despite the huge burden of congenital anomalies in LMICs, there is still a dearth of comprehensive data on these conditions as birth defects registries are absent . There iWe aimed to assess the prevalence, pattern, risk factors and outcome of congenital anomalies among neonatal admissions in a Tertiary Hospital in a semi-urban area, South-West, Nigeria.This study was conducted at the Neonatal Unit of the Bowen University Teaching Hospital (BUTH), Ogbomoso. BUTH is a faith-based tertiary institution, which is located in semi-urban Ogbomoso, in Oyo State, South-West Nigeria. The institution provides multi-specialist care and serves as a major referral center for hospitals within and outside Ogbomoso, including towns in three states. The hospital was initially established as a general hospital in 1907 but was upgraded to a teaching hospital in 2009. The neonatal unit provides care for neonates delivered within and outside the hospital. However, babies requiring ventilator support and other intensive care are referred elsewhere.This was a cross-sectional study, conducted by retrospectively reviewing the medical records of all neonates admitted at the neonatal unit of BUTH over a five-year period between January 2012 and December 2016. Ethical approval for the study was obtained from the institutional research ethics committee. For the purpose of this study, congenital anomalies were defined as structural defects that were present at birth or identified during the neonatal period, either clinically or through investigation modalities. Categorization of these anomalies was then done using the European Surveillance of Congenital Anomalies (EUROCAT) guidelines . PerinatData were collected on neonatal, birth and maternal characteristics, congenital anomaly status and the outcome of the admission were obtained. Information on neonatal characteristics obtained included: sex, age at presentation, gestational age at birth, birth weight, and type of gestation, place of birth and mode of delivery. Maternal factors obtained were age, parity, antenatal care, folic acid use, febrile illness during pregnancy, self-medication and lifestyle variables, such as smoking and alcohol intake during pregnancy. The outcome variables were the status at discharge ; and the mortality experience.p < 0.2, and significant variables were included in a multivariate Cox regression analysis to determine the predictors of 28-day mortality among neonatal admissions at p < 0.05. The level of significance was set at p < 0.05.Data collected were analyzed using the SPSS version 21. Categorical variables were summarized using frequencies, ratios and proportions, along with the 95% confidence interval. Continuous variables were summarized using mean, standard deviation, or median and interquartile range (IQR). The prevalence rate of CA was calculated as the proportion of neonates with CA among the total number of neonates admitted during the study period. Associations of neonatal characteristics and maternal socio-demographic factors with congenital anomalies were tested using the chi square statistic. Risk factors were assessed using the binary logistic regression, and the odds ratio and 95% confidence intervals were reported. Bivariate Cox regression analysis was used to assess variables that were significantly associated with neonatal mortality at p < 0.05). The mothers were mainly of the Yoruba ethnic group (89.6%) and 71.6% were domiciled within the town of study.Figure Anomalies of the cardiovascular system were the commonest anomalies in this cohort, occurring in 14 20.9%) of the neonates with CAs (Table 0.9% of tGlucose-6-phosphate dehydrogenase (G6PD) deficiency, a metabolic CA, occurred in 50 (4.7%) of the patients. Diagnosis of this condition was established using a qualitative screening test. No quantitative assay had been done on these patients. These neonates were, however, not included in analysis of CAs as the study focused on only structural anomalies.p > 0.05)  Table . Young mp < 0.0001). A total of 111 neonates died during the study period, including seven neonates with CA, giving an overall mortality rate of 10.5%. One hundred and nine of the deaths occurred during the neonatal period, giving a neonatal mortality rate of 10.3%. CA accounted for 5.5% (6/109) of all the neonatal deaths. Prematurity and perinatal asphyxia were the leading cause of neonatal death in this series [Fig. Forty-seven (70.1%) of the neonates were discharged home after initial treatment; six (9%) departed against medical advice; seven (10.4%) were referred and seven (10.4%) died. Neonates with congenital anomalies were more likely to be referred when compared with only 0.1% referred among other neonates  among patients with CA was 9% (6/67) as shown in Fig. Nigeria ranks only second to India in the absolute number of annual neonatal deaths worldwide , 27, 28.Prevalence studies such as this, help to determine baseline rates and to identify changes over time, which are essential in public health planning of preventive and eradication strategies. This study demonstrates the prevalent nature of birth anomalies. However, we may have significantly under-estimated the actual incidence of these anomalies in the general population. Being a tertiary health facility, complicated cases are more frequently seen, while the uncomplicated cases may have been treated in other peripheral facilities. Anomalies that did not require hospitalization were not captured in this study except where they co-existed with conditions requiring immediate treatment. We also did not include abortions and stillbirths in this study. Previous studies have, however, shown that the incidence of CA is higher among stillbirths and abortuses , 17, 30.The most common anomalies were those of the cardiovascular system, followed by those of the digestive system. This finding was similar to those reported in studies from the United States, Lebanon and the United Kingdom, in which larger cohorts were analyzed , 18, 31.Related to this, however, is the very significant finding of neonates with the functional anomaly of G6PD deficiency. Almost 5 % of all the neonates had this anomaly, which almost equates the 6.3% contributed by all structural anomalies in this study. This is in keeping with earlier studies on G6PD in Nigeria, where incidences of 24 and 5% were reported in males and females, respectively . The higThe significant association between low birth weight (LBW) and congenital malformations has been well-documented , 17, 18.It is generally known that maternal lifestyle may predispose to development of CA in their offspring. The consumption of alcohol, cigarette and certain medications are known teratogenic factors , 18, 21.p = 0.077). Some studies have shown significant association between multiparity and the occurrence of congenital anomalies but the authors did not control for the effect of maternal age as a confounding factor [We did not find any significant association between CA and maternal age, parity, febrile illness, preterm delivery and type of gestation. The mean maternal age was 29.8 (±5.4) years, which falls within the active reproductive years. Many studies have shown an increase in the incidence of birth malformations with increasing maternal age, particularly in mothers older than 35 years –16, 21. g factor .Birth defects have been shown to have significant effect on morbidity and mortality . We asseA majority of neonates (70%) with birth defects were discharged home after initial management in our facility. The overall mortality rate among neonates with CA was 10.4%. This was almost comparable to the 16.9% observed in Ibadan . MortaliThe male sex was associated with a higher risk of mortality compared to female neonates. As expected, the presence of co-morbidity increased the risk of neonatal death but did not independently predict the risk. Each additional week of gestation at birth, however, was associated with a 14% reduced risk of neonatal death. Severe perinatal asphyxia increased the risk of neonatal mortality by over five times Additional file 2:Spreadsheet of study data in .dat format. (DAT 147 kb)


Varanus) inhabited Europe at least from the early Miocene to the Pleistocene. Their fossil record is limited to about 40 localities that have provided mostly isolated vertebrae. Due to the poor diagnostic value of these fossils, it was recently claimed that all the European species described prior to the 21st century are not taxonomically valid and a new species, Varanus amnhophilis, was erected on the basis of fragmentary material including cranial elements, from the late Miocene of Samos (Greece). We re-examined the type material of Varanus marathonensis Weithofer, 1888, based on material from the late Miocene of Pikermi (Greece), and concluded that it is a valid, diagnosable species. Previously unpublished Iberian material from the Aragonian (middle Miocene) of Abocador de Can Mata  and the Vallesian (late Miocene) of Batallones (Madrid Basin) is clearly referable to the same species on a morphological basis, further enabling to provide an emended diagnosis for this species. Varanus amnhophilis appears to be a junior subjective synonym of V. marathonensis. On the basis of the most complete fossil Varanus skeleton ever described, it has been possible to further resolve the internal phylogeny of this genus by cladistically analyzing 80 taxa coded for 495 morphological and 5729 molecular characters. Varanus marathonensis was a large-sized species distributed at relatively low latitudes in both southwestern and southeastern Europe from at least MN7+8 to MN12. Our cladistic analysis nests V. marathonensis into an eastern clade of Varanus instead of the African clade comprising Varanus griseus, to which it had been related in the past. At least two different Varanus lineages were present in Europe during the Neogene, represented by Varanus mokrensis (early Miocene) and V. marathonensis (middle to late Miocene), respectively.Monitor lizards (genus  Varanus (Varanidae) originated as early as the late Eocene [Varanus amnhophilis Conrad et al., 2012 , Varanus atticus Nopcsa, 1908 ; Varanus deserticolus Bolkay, 1913 ; Varanus hofmanni Roger, 1898 ; Varanus lungui Zerova & Chkhikvadze, 1986 ; Varanus marathonensis Weithofer, 1888 ; Varanus mokrensis Ivanov et al., 2018 ; Varanus semjonovi Zerova & Chkhikvadze, 1986 ; and Varanus tyrasiensis Lungu et al., 1983 . Except for V. amnhophilis, V. marathonensis and V. mokrensis, all the other nominal species are represented by isolated vertebrae only, or by material which is not clearly referable to Varanus.Monitor lizards have a wide current distribution embracing Africa, Asia, and Australia . The cure Eocene  and thate Eocene –6. The Ee Eocene ,7–9. NevVaranus, based on a combined data set of morphologic and molecular data [Varanus vertebrae are diagnostic to species”. Conrad et al. [Varanus species, but such characters just identify species groups, not species. An example is provided by the only unambiguous morphologic synapomorphy that diagnoses a subclade of Varanus: the “presence of strong precondylar constriction of the presacral vertebrae such that a right or acute angle is formed between the condyle and the centrum just anterior to the posterolateral part of the condyle (state 2 of character 233)”  remarkeVaranus erected based on European materials are not diagnosable (this statement predates the description of V. mokrensis). Based on this assumption, Conrad et al. [V. amnhophilis, from the late Miocene locality Q1 of Samos , which  ~7.1 Ma , such maV. amnhophilis overlooked that V. marathonensis, from the late Miocene (MN12) of Pikermi  was est and the Madrid Basin . As briefly anticipated by Delfino et al. [Varanus skeleton ever described, that the species erected by Weithofer [V. amnhophilis. Furthermore, the phylogenetic relationships of this species with other fossil and extant Varanus are evaluated based on a cladistic analysis including both morphologic and molecular data, and the paleobiogeographic history of Neogene European monitor lizards is discussed.In order to provide a solid ground for the study of the European monitor lizards, here we re-evaluate the morphology of the type material of o et al. ,17, we seithofer  is (1) dVaranus species have been studied as comparative material. A complete list of these specimens is given in The studied material includes varanid remains coming from the Miocene of Greece and the Iberian Peninsula. The Greek material is stored in the Institut für Paläontologie der Universität Wien, in Vienna, whereas the Iberian material is stored in the collections of the Institut Català de Paleontologia Miquel Crusafont in Barcelona  and of the Museo Nacional de Ciencias Naturales in Madrid . Further material from Greece that is stored in the National History Museum of Aegean, Mytiliniii, Samos Island, is mentioned in the discussion, even though it is not studied in detail in this paper. More than 200 skeletons of extant Varanus semiremex, which is better resolved in our analysis. The strict consensus tree presents exactly the same topology as in Conrad et al. [We used the matrix of Conrad et al.  to perfod et al. . Conrad d et al.  did not Varanus mokrensis as taken from Ivanov et al. [Varanus marathonensis, named “Vmarathonensis Vamnhophilis”, mainly based on the information provided by the new skeleton from Batallones, but also including the scorings for a few additional characters as provided by the type of Varanus amnhophilis, here considered a synonym of V. marathonensis (see below), for our main analysis . The skeleton from Batallones is considered representative also for the rest of the material assigned to V. marathonensis , given that their scorings are redundant , the last three characters of the matrix were deactivated. These three characters corresponded to the last one in the matrix provided by Conrad , and two new characters added herein. A variation of the same analyses was performed in order to test the influence of the addition of the new characters. The second set of analyses  comprises the same as above, but with the last two morphological characters of the matrix (added in the present work) activated  coding for the fossil v et al. , except t (sensu ) and allated see .The anatomical terminology follows the one used in Conrad’s works ,11. AnatACM, local stratigraphic series of Abocador de Can Mata ; BAT, Cerro de los Batallones ; C2, C3, C4, C5, different cells from ACM .CM, Carnegie Museum of Natural History ; ICP, Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona ; IPS, ‘Institut de Paleontologia de Sabadell’, acronym of the collections of the ICP; IPUW, Institut für Paläontologie der Universität Wien ; MNCN, Museo Nacional de Ciencias Naturales–CSIC ; SMF, Senckenberg Museum Frankfurt (Germany); ZFMK, Zoologisches Forschungsmuseum Alexander Koenig .The Vallès-Penedès Basin  is a half-graben that originated as a result of the extensional tectonics that started by the earliest Neogene in the Western Mediterranean, due to the northward movement of the African plate –24. The Megacricetodon crusafonti + Democricetodon crusafonti Interval Subzone of the Vallès-Penedès Basin [The Vallès-Penedès Basin has delivered a rich fossil record of terrestrial vertebrates from the early to the late Miocene ,27. The ès Basin ,36), repVaranus material described in this paper comes from BAT-3, which on the basis of micromammalian remains [Cerro de los Batallones  includes a set (BAT-1 to BAT-10) of exceptionally rich paleontological sites of Vallesian age , right maxilla; IPS50292 (from ACM/C3-A6), right maxilla; IPS57544 (from ACM/C3-A7), tooth-bearing bone; IPS42353 (from ACM/C4-C2), trunk vertebra; IPS42362 (from ACM/C4-C2), trunk vertebra; IPS43719 (from ACM/C4-C2), trunk vertebra; IPS57546 (from ACM/C2-A3), trunk vertebra; IPS42400 (from ACM/C4-C2), caudal vertebra; IPS49408 (from ACM/C2-A3), caudal vertebra; IPS42368 (from ACM/C4-C2), caudal vertebra; IPS57547 (from ACM/C2-A3), caudal vertebra; MNCN BAT-3 1088, right and left maxillae, right prefrontal; MNCN BAT-3 2011–200, premaxilla, right and left maxillae, right and left frontals, left lacrimal, right and left prefontals, right supraorbital, right and left postorbitofrontals, parietal, right and left quadrates, parabasisphenoid, supraoccipital, right and left prootics, right and left otooccipitals, basioccipitas, left palatine, left pterygoid; MNCN BAT-3 2011–252, right and left dentaries, right and left coronoids, right surangular, right prearticular, right articular; MNCN BAT-3 2011–148, right coracoid, left humerus, right and left ilia, right and left femura, right and left tibiae; MNCN BAT-3 2011–2626, six cervical vertebrae (axis included); MNCN BAT-3 2011–2627, 20 trunk vertebrae; MNCN BAT-3 2011–2628, last trunk vertebra, two sacral vertebrae, one cloacal vertebra (plus a fragment of a possible second one), first caudal vertebra; MNCN BAT-3 2011–2629, 51 caudal vertebrae and few chevron bones. All the Batallones material except MNCN BAT-3 1088 was found associated and belongs to a single individual.Type locality and age. Pikermi, near Athens (Greece). Geographic coordinates are 38°01’10”N, 23°59’30”E according to the NOW database [database . Accordidatabase , the latdatabase .Age and distribution. Late Miocene (MN12) of Greece . Middle to late Miocene (MN7+8 to MN10) of Spain .Emended diagnosis.Varanus marathonensis differs from all the extant and other fossil Varanus (for which the maxilla is known) by two maxillary autapomorphies: anterior sloping surface of the facial process characterized by a medially directed, very broad and slightly concave lamina, whose medial edge can be ventrally thickened by a ridge in larger specimens; distinct lateral sulcus developed along the narial margin, anteriorly shallow but more evident posteriorly, where it is delimited by ridges. Moreover, it differs because of the following combination of maxillary characters: crista lateralis of the lateral premaxillary process not developed apically; well-developed, high and laminar crista transversalis on the medial anterior maxillary process. Additional characters: nine to 10 slender, mediolaterally flattened, non-molariform maxillary teeth; anterior edge of the facial process gently sloping ).V. marathonensis: 1) Parietal, transverse posterior margin between the supratemporal processes, absent, no transverse posterior margin between the supratemporal processes; 2) Braincase, occipital condyle, single unit made of basioccipital and otooccipitals; U-shaped; 3) Prootic, facial foramen, single; 4) Prootic, accessory anterostapedial process shape, anteroposteriorly elongate tab that is laterally directed; 5) Prefrontal, anterolateral overlap of the frontal, with strong dorsomedial flange partly constricting the exposed frontal margin; 6) Groove on the lateral surface of the maxilla in the anterior sector of the bony narial opening, present; 7) Medial expansion on the anterior sloping edge of the facial process of the maxilla, present, developed on the ascending branch of the process, and well defined posteriorly .The phylogenetic analysis recovered the following unambiguous apomorphies for Varanus marathonensis was introduced in the literature by Weithofer in 1888 [Varanus? Vertèbre qui ressemble à celles des grands varans de l’Afrique”. Such vertebra is still available in the collections of the Muséum national d'Histoire naturelle  with the accession number “MNHN Pikermi n. 31”. Fejérváry [V. marathonensis [V. marathonensis [V. marathonensis and “treated the partial skull separate from the presumed holotypic vertebra because there is no clear reason to associate them”.The name  in 1888 . He desc in 1888 ) two fos in 1888  and figuejérváry  correctlejérváry ) but othhonensis  or refighonensis . More rehonensis  erroneouIPUW 1888-001-001 is a left incomplete maxilla, 39.80 mm long, preserved on a block of hardened reddish sediment along with a few other unidentified bone fragments . The maxWeithofer  also desVaranus marathonensis as topotypes. The three better-preserved vertebrae  of the maxillae analyzed in this study . The eleThe second maxilla IPS50292  is smallIPS57544 is represented by two tooth-bearing bone fragments. The largest corresponds to two tooth positions, the smallest just to one. None of them preserves a complete tooth, but both show the remnants of labiolingually-compressed teeth with longitudinal basal striations. Due to erosion, such striations are well visible, and one of the two teeth of the largest fragment, broken nearly transversally, clearly shows the internal lamellae typical of the plicidentine.None of the available four trunk and four caudal vertebrae  is complCaudal vertebrae  are charThe two fragmentary maxillae from BAT-3 apparently belong to a single individual. The right maxilla BAT-3 1088a  is betteBAT-3 1088b is represented just by a portion of palatal shelf corresponding to eight tooth positions and a little part of the facial process. Just the third preserved position hosts a tooth. None of the characters described above can be discerned on this element.Two unnumbered isolated teeth and about a dozen bone fragments likely belong to these two maxillae.The right prefrontal BAT-3 1088c is a rather well preserved triradiate element . The maiThe nearly complete skeleton from Batallones-3 is represented by at least 119 skeletal elements, originally found close to each other, corresponding to the following collection numbers MNCN BAT-3 2011–200, –252, –148, –2626, –2627, –2628, and –2629.Premaxilla–The premaxillae . The transverse process is rather thick and tall laterally. Its lateral edge is flattened and develops dorsally in a sort of lamina and ventrally in a rounded expansion. The lateral margin of the transverse process is convex, whereas the medial one, hosting the contact facet with the ectopterygoid, is concave. Both the dorsal and ventral surfaces of the main body of the pterygoid are somewhat concave. The edge of the pterygoid between the transverse and the palatine processes is laminar and concave. The posteromedial edge of the transverse process is thicker than the anterolateral one. A distinct ridge runs along the quadrate process, presumably at the ventromedial edge, and the medial surface is weakly concave dorsal to it.reserved , being rEctopterygoid–BAT-3 2011–200r is a right, partially preserved ectopterygoid .frontals  are wellfrontals . This inPostorbitofrontal–Both the right and left elements preserve their anterior portion, which is characterized by the three evident processes: the anterolateral process, the frontal process and the parietal process . MoreovParietal–This unpaired bone is nearly perfectly preserved  and their preserved tips are 33.80 mm from each other, so that the anterior width of the bone is smaller than the posterior one. The processes are directed posterolaterally in dorsal view and slightly ventrally in lateral view. The posterior angle between the processes is about 90°. Their short axis is ventrolaterally directed. They are somewhat rounded dorsally (but not broad or flat) and rather sharp ventrally. The facets for the contact with the supratemporal extend anteriorly at the level of (on the left) or well beyond (on the right) the anterior limit of the processes, and occupy most of their lateral surface. The contact facets at the distal tip of the supratemporal processes are not preserved or visible with confidence, except for the supratemporal facet that could be present on the left process. The ventral surface of the parietal hosts at its lateral edges, anteriorly to the supratemporal processes, the descensus parietalis , a moderately deleveloped crest nearly anteroposteriorly oriented. The fossa parietalis opens posteriorly and is delimited ventrally by a well-developed ridge, the crista juxtafovealis that gives origin to the crista postfovealis, running along the medial surface of the supratemporal processes.Braincase–The braincase is represented by the isolated parabasisphenoid  is smooth and devoid of any sagittal ridge or recess . The basThe sutures between the supraoccipital and the surrounding elements are well visible . This unV. amnhophilis; [Both the prootics preserve the long, anterodorsally and relatively pointed alar process, each distinctly overhanging the relative inferior process . The fenophilis; ). The prThe tip of the right paroccipital process is not complete but the isolated portion of the left one is perfectly preserved and shows that its dorsal and ventral tips extend equally posterolaterally . The venBoth sphenooccipital tubercles are preserved. They are evident but comparatively small and clearly directed ventrally. They are placed at the anteroventral tip of the tuberal crest. The occipital condyle is proportionally strong and very well defined. It is made ventrally by the basioccipital and laterally by the otooccipitals. The general shape is that of a broad U .The tuberal crests  are lateDentary–The two dentaries are isolated and rather well preserved . The right element  opens oCoronoid–Both coronoids are preserved  and by a strong precondylar constriction. The ratio bewteen the minimum precondylar width of the centrum and the maximum condyle width varies, in the four vertebrae that can be measured, from 70.8% to 75.6% . The centrum length is difficult to measure because most of the vertebrae are preserved in connection. Nevertheless, the length of the longest centrum may reach 15.30 mm.A block of vertebrae cemented by matrix . The distal end of the right diapophysis has the shape of a V laying on one side, with the concavity oriented in posterior direction. The dorsal branch of the V is more robust and longer than the ventral one. The second sacral vertebra is better preserved and exposed than the first one. The estimated length of the centrum could reach approximately 15 mm. The diapophyses are slightly bent downward and their distal tip is simply anteroposteriorly elongated. The maximum width at the level of the diapophyses in the second sacral vertebra is of 37.50 mm. Two short longitudinal (following the main axis of the structure) ridges are located at mid length of each diapophyses, close to its posterodorsal and posteroventral edges. At least one vertebra associated to the sacral ones is interpreted as a cloacal vertebra lacking pedestals for chevron bones and synapophyses, but bearing transverse processes. It also lacks lymphapophyses.Nearly all the tail is preserved on a slab where 51 vertebrae can be counted , it forms a trichotomy with the group formed by V. bengalensis + V. nebulosus + V. dumerilii + V. flavescens and the V. salvator complex + V. rudicollis. The majority rule consensus tree  are recovered as sister taxa, suggesting they might represent the same species. Alternatively, this could be interpreted as indicating a high degree of phylogenetic closeness, but still different species. The evidence reported in the present paper (see V. amnhophilis and V. marathonensis in the same position as V. marathonensis (coded as merged: "Vmarathonensis Vamnhophilis") in analysis 1A. In any case, more than 50% of the trees (as reported by the Majority rule consensus tree) support a position inside the Indo-Asian clade, and, more specifically, again as sister to the group formed by V. bengalensis + V. nebulosus + V. dumerilii. The second set of analyses  yielded trees that are two steps longer, but similar in terms of topology and percentage of trees supported in the majority rule consensus trees. A list of the apomorphies recovered for V. marathonensis and the synapomorphies of the clade containing V. marathonensis and the subgenus Indovaranus as well as those of the Varanus clade are given in the supporting information  and Varanus bengalensis , whose maxillae are briefly described below.The recovery of monitor lizards remains in the late Miocene of Pikermi, close to Athens (Greece), was already mentioned by Gaudry , who pruanus sp. ,59,60. Fanus sp.  carefulleithofer  clearly eithofer ), the Ib species ,61–65. Ocies see  confirmscies see , none ofV. griseus (V. marathonensis) in all studied specimens . The concavity, which hosts a lateral expansion of the septomaxilla, is parallel with the medial concavity and ventral folding of the palatal shelf. In the two disarticulated specimens of V. griseus  examined, it is clear that the dorsal lamina is not confluent with the palatal shelf (as in V. marathonensis IPS50119) and that a foramen opens between the medially expanded lamina and the palatal shelf. However, the medially expanded area (posterior to the concavity) is only partly located on the anterior sloping surface of the facial process and is mostly developed on the horizontal surface, anterior to the facial process itself. This is different from the situation in V. marathonensis, in which it develops on the sloping surface. Such widened surface, significantly smaller than in V. marathonensis, develops nearly horizontally (not inclined as in V. marathonensis) and can be slightly concave (an exception being ZFMK 7848). The surface is delimited anteriorly by a variably developed step (located at the level of the fifth tooth position) and frequently also by a lateral ridge, even in the smallest available specimen . An exceptionally developed ridge is present in SMF 74486. In lateral view, the step corresponds to a small dorsal convexity of the upper profile of the maxilla. In ZFMK 7848, this surface is nearly flat on the left maxilla and irregularly concave on the right maxilla, where the bone clearly shows a healed fracture that probably resulted in the depression.The maxilla of  griseus  is long Varanus bengalensis, in turn, has a very peculiar morphology (V. griseus and V. marathonensis). However, the development of such lamina does not reach the extent seen in V. marathonensis and, in dorsal view, there is only a week medial concavity between the lamina and the crista transversalis.rphology . The criVaranus marathonensis Weithofer, 1888 is a taxonomically valid, diagnosable species. Moreover, thanks to the new Iberian material, it is possible to associate other characters to V. marathonensis (see Diagnosis). It is noteworthy that a lateral sulcus in the anterior sector of the narial opening is present. It is a character unknown in any other fossil Varanus species so far described nor in any of the extant Varanus species directly examined during this study  is shown in Varanus rusingensis Clos, 1995 , the maxillary morphology of which is not known in detail, but that is characterized by the presence of blunt posterior teeth [Finally, all the teeth of identine  and are or teeth .V. marathonensis and V. mokrensis are the only European species so far described on the basis of diagnostic remains. Most of the remaining nominal species are either junior synonyms of V. marathonensis or, being based on isolated vertebrae that are not diagnostic at the species rank, best considered nomina dubia .The question remains as to how many monitor species from the Neogene of Europe can be considered valid from a taxonomic viewpoint. Although other eight nominal species have been erected on the basis of European Neogene materials, it is likely that Varanus amnhophilis Conrad et al., 2012 from Samos was anticipated by Conrad et al. [V. marathonensis, and chronological and geographic proximity of the Q1 locality of Samos and Pikermi , Delfino et al. [V. marathonensis before formal erection. However, Conrad et al. [V. marathonensis from its diagnostic cranial type material  and associated it to Gaudry’s non-diagnostic (at least at species level) vertebra. This opened the way to the erection of the new species V. amnhophilis without comparing it with Weithofer’s material and with the European fossil record of V. marathonensis. The diagnosis of V. amnhophilis is non-differential, but based on a combination of apomorphies that we know now are shared with V. marathonensis . Further support for the synonymization of V. amnhophilis with V. marathonensis is provided by additional, still unpublished material from Samos, hosted in the collections of the Natural History Museum of Aegean, Mytilinii, Samos Island. This material, which will be the subject of a forthcoming publication, comes from another locality of the Mytilinii Formation and comprises the anterior region of a skull  is here considered a junior subjective synonym of V. marathonensis Weithofer, 1888. It is worth mentioning that the size of the Samos remains described by Conrad et al. [V. marathonensis from ACM, at least on the basis of the centrum length  of the  species ).Varanus atticus Nopcsa, 1908 was introduced in the literature just to name the vertebra already described and figured by Gaudry [Varanus sp. Nopcsa [Varanus atticus Nopcsa, 1908 is here considered a junior subjective synonym of Varanus marathonensis Weithofer, 1888, as previously concluded by de Fejérváry [y Gaudry  as Varan. Nopcsa , who did. Nopcsa  had alreejérváry , Hoffsteejérváry , and Ragejérváry . Note thVaranus deserticolus Bolkay, 1913 is rather doubtful. It was erected on the basis of a fragmentary dentary with two teeth .omplete,  and Młynomplete, , it actuomplete, , p. 222)omplete, , it is nm. Estes  and MolnVaranus hofmanni Roger, 1898 is represented by vertebrae characterized by a depression, with an angulate posterior end, developed in the anterior region of the neural arch . Thisee also –76). How[Varanus ,10, it iVaranus lungui Zerova & Chkhikvadze, 1986, Varanus semjonovi Zerova & Chkhikvadze, 1986 and Varanus tyrasiensis Lungu, Zerova & Chkhikvadze, 1983 have been summarized and discussed by Molnar [V. tyrasiensis was originally erected was actually variable in the comparative material that they had later at their disposal.The characteristics of the Eastern European species y Molnar  themselvVaranus mokrensis Ivanov et al., 2018 is based on a large collection of both cranial and postcranial elements and, as such, can easily be compared with V. marathonensis. The single autapomorphy of this species, the acute angle between the parietal and squamosal processes of the postorbitofrontal, is absent in V. marathonensis, the processes of which make in contrast a widely obtuse angle. Based on the figured maxilla and on the descriptions given by Ivanov et al. [V. mokrensis, but the lateral sulcus along the narial margin is distinctly absent. Moreover, V. marathonensis differs from V. mokrensis in other significant features, among which: parietal with narrower anterolateral processes , straight anterior margin (convex in V. mokrensis), and a pineal foramen that is closer to the anterior margin; absence of a distinct crest on the base of the paroccipital process as seen in posterior view; slightly less prominent iliac crest on the ilium. Varanus mokrensis is also distinctly smaller in size [V. marathonensis and V. mokrensis as distinct species.The recently described v et al. , it is n in size . AdmitteVaranus catalaunicus  is a nomen dubium. This species was erected by Hoffstetter [Iberovaranus Hoffstetter, 1969 on the basis of an isolated trunk vertebra. However, Delfino et al. [Varanus. Because of this, they synonymized Iberovaranus with Varanus. The vertebral material described by Hoffstetter [V. catalaunicus as a nomen dubium. Nevertheless, it is interesting to note that the size of the holotypic vertebra of V. catalaunicus is strongly smaller than the largest trunk vertebrae of V. marathonensis (10.60 mm contra 18.36 mm), approaching the vertebral size of a medium-sized monitor lizard like the roughly coeval V. mokrensis from the Czech Republic.fstetter  within to et al.  later defstetter  and Delffstetter  is not sfstetter  view in V. marathonensis and V. mokrensis currently seem to be the only taxonomically valid European species of monitor lizard, the other nominal taxa previously erected from the European Neogene being either junior synonyms  of the former, or nomina dubia. However, the only remains clearly referable to V. marathonensis are those represented at least by maxillae or sharing with V. marathonensis a significant portion of cranial characters, i.e., those from Pikermi (Greece), Abocador de Can Mata , Batallones-3 , and Samos (Greece). The referral to V. marathonensis of very fragmentary cranial elements, isolated vertebrae, or sections of vertebral columns from the early Pliocene of Csarnóta 1 . Identified as V. marathonensis by Morelli [To sum up, Hungary; ) and ÇalHungary; ) should  Morelli , it is c Morelli .Varanus, including the extinct Varanus priscus , the internal phylogeny of the genus is still unclear [Even though there is a general morphology- and molecule-based consensus on the monophyly of  unclear ,58,81,82 unclear , grouped unclear ,64. Comb unclear ).V. griseus, a species with a geographic range that currently approaches Europe, including also the southern and eastern Mediterranean countries [Varanus marathonensis in the same clade as V. griseus, along with another extinct species, Varanus darevskii Levshakova, 1986, from the Pliocene of Tadjiikistan.Such unstable phylogeny seriously hampers deciphering the phylogenetic relationships between European fossil monitor lizards and extant taxa. A priori, it would be expected to find close relationships between the European taxa and the clade of the African forms , which countries ,85. Actuountries  proposedV. amnhophilis in the Indo-Asian A clade and what they considered to be the type of V. marathonensis  nested into the Australasian clade. The cranial material that actually represents the lectotype of V. marathonensis (labeled ‘Varanus’ cf. marathonensis in their tree) fell well outside of crown Varanus (probably related to the large amount of missing data). Based on their phylogenetic results, Conrad et al. [Varanus as a whole and Asian affinities for the European species. These hypotheses seemed to be confirmed by the phylogenetic analysis of Ivanov et al. [V. mokrensis was found as a member of the Indo-Asian A clade but is basal to African varanids, including the extinct V. rusingensis from the early Miocene of Kenya. All these analyses found V. amnhophilis and V. marathonensis  to be phylogenetically well apart.Conrad et al.  recovered et al.  suggestev et al. , in whicV. amnhophilis, and the position of the clade composed by them inside the Indo-Asian A clade is rather stable. More specifically, a sister group relationship with the clade formed by V. dumerilii, V. bengalensis, and V. nebulosus is well supported. Regarding V. mokrensis, it is invariably recovered as the most basal non-African taxon, sister to the group formed by the Indo-Asian B, Indo-Asian A and Indo-Australian groups . This would strongly suggest that European Varanus include at least two different lineages: one would be represented by V. mokrensis; the other one would be represented by, according to our results, V. marathonensis.Problems arising from the inclusion of fragmentary remains in phylogenetic analyses based on large datasets have been already stressed . As expV. mokrensis is different from that recovered by Ivanov et al. [V. mokrensis that were not scored by Ivanov et al. [Varanus mytilini and Varanus amnhophilis, when the former actually was the name for V. amnhophilis in Conrad et al.’s [The position recovered here for v et al. . Howeverv et al. ; and 5) et al.’s  matrix, Varanus is one of the most debated issues concerning the evolution of varanid lizards [Varanus [Varanus taxa in molecular phylogenies [The historical biogeography of  lizards ,87. The [Varanus  could sulogenies ,88. Howelogenies ), as applogenies , 11. Smilogenies  also disVaranus nor the alternative hypothesis of an African origin for the genus. The sister taxon to Varanus recovered in most of the recent phylogenetic analyses, including the one we are presenting here and that performed by Conrad et al. [Saniwa ensidens, from the Eocene of North America. The roughly coeval European Saniwa orsmaelensis was not included in the phylogenetic analysis but Saniwa went extinct in Europe at the end of the Eocene [Varanus appears in the European fossil record only in the early Miocene [Varanus.It has to be noted, however, that our phylogenetic analysis is neither supporting a Eurasian origin for d et al. , is Sanie Eocene , whereas Miocene . The fac Miocene  does notVaranus clade is composed by African taxa. Thus, an African origin of Varanus cannot be discounted. However, the position we recovered for V. mokrensis  is at odds with the ancestral condition inferred by Ivanov et al. [Varanus. Our cladistic analysis recovered V. mokrensis and V. marathonensis as belonging to two different lineages without a direct ancestor-descendant relationship, thus suggesting that a different geographic origin for the two valid European Varanus species may be possible.Moreover, in both our analysis and in Conrad et al.’s , the mosv et al.  for the v et al. , and theVaranus, Rage [Varanus species from the Neogene of Europe  indicate a possible link with an Indo-Asian clade of Varanus. This fits with the hypothesis of a Eurasian origin of the genus. The presence of a Varanus of Asian origin in the European Neogene agrees well with other, well-documented dispersal events of the herpetofauna from Asia into Europe , from the MN7+8  in Spain to the MN12  in Greece, suggests that many of the available European Miocene Varanus remains might belong to this species. Regardless, although Varanus marathonensis was distributed at relatively low latitudes in both Western and Eastern Europe from the MN7+8 to the MN12, it emerges that the genus Varanus displayed a greater chronological and geographic distribution in this continent when all the European record is taken into account.Although, on the basis of available diagnostic material, the presence of Varanus in Central Europe corresponds to the late Miocene, whereas in Southern Europe it survived until the Middle Pleistocene [Varanus material. It would be interesting to test whether the post-Miocene material, especially the Quaternary one, belongs to V. marathonensis, testifying its prolonged permanence in at least the southern part of Europe, or whether it represents a dispersal of other species, more closely related to extant taxa. In the case of the last occurrence of a varanid in Europe , an attrphology .Varanus almost reached the 49th parallel  between MN4 and MN10, i.e. for an extended period of time broadly encompassing the Mid-Miocene Climatic Optimum [Varanus corresponds to an unspecified site in the area of Moreda , wh, Spain; ,108–113.Varanus marathonensis Weithofer, 1888, originally erected on the basis of late Miocene material from Pikermi (Greece), is currently one of the two only European Varanus species that can be considered taxonomically valid. The other is V. mokrensis from the early Miocene of the Czech Republic. The revision of the syntype of V. marathonensis  allowed us to confirm the presence of a character already originally described by Weithofer [Varanus. The description of previously unpublished conspecific materials, including maxillae, from the latest middle Miocene stratigraphic series of Abocador de Can Mata  as well as from the late Miocene of Cerro de los Batallones , confirms the validity of V. marathonensis and implements the diagnosis of this taxon with the inclusion of several new characters. The majority of the remains from Cerro de los Batallones 3 can be referred to a single individual that, being represented by nearly all the skeletal elements, is the most complete Varanus skeleton ever described in the world.eithofer , which hV. marathonensis could be sought in an eastern clade of Varanus instead of the African clade comprising V. griseus, to which it had been related in the past. Regardless of its phylogenetic relationships, our results indicate that V. marathonensis was distributed both in Western and Eastern Europe at least for about 5 Myr, from the middle to the late Miocene, whereas on the whole the genus Varanus inhabited Europe at least from the early Miocene to the late Miocene in Central Europe, further persisting until the Middle Pleistocene in Southern Europe. Due to such a wide geographic and chronological range of V. marathonensis, most of the European fossils of Varanus may belong to this species, at least as far as the Neogene occurrences are concerned. Therefore, comparisons with this taxon are required before erecting additional extinct European species of Varanus in the future. Nevertheless, the presence in Europe of a second valid species, V. mokrensis, in the early Miocene and of remains not clearly attributable to V. marathonensis in the Middle Pleistocene demonstrate that other species were indeed represented in the continent.The phylogenetic relationships of S1 File(PDF)Click here for additional data file.S2 File(PDF)Click here for additional data file.S3 File(NEX)Click here for additional data file.S4 File(PDF)Click here for additional data file.S5 File(PDF)Click here for additional data file.S6 File(PDF)Click here for additional data file.S7 File(PDF)Click here for additional data file.


In Ethiopia, large scale health care efforts had been done to promote infant health and survival. However, nationwide data is lacking on the survival status and proximate determinants of infant mortality in Ethiopia. Therefore, this study was aimed to identify the survival status and determinants of infant mortality in Ethiopia using Ethiopian Demographic and Health Survey (EDHS).The data source for this study was the 2016 Ethiopian Demographic and Health Survey. Records of all 10,641 live births and survival informations of all 2826 infants born 5 years before the survey were reviewed. Kaplan-Meier method and Cox proportional hazards regression model were employed to identify the proximate determinants associated with the infant mortality.The results of Kaplan-Meier estimation showed that the highest infant deaths occurred in the early months of life immediately after birth and declined in the later months of follow-up time. About 65% of infant deaths occurred during the first month’s of life. Using the Cox proportional hazard model we found that: mothers’ level of education, preceding birth interval, plurality, size of child at birth and sex of child as significant predictors of infant mortality. The risk of dying in infancy was lower for babies of mothers with secondary education , higher education , for preceding birth interval longer than 47 months  and higher for birth interval shorter than 24 months , for multiple births , for very small size of infants , for smaller than average size infants  and for female infants  compared to the reference category.A significant proportion of infants died during the study period of which nearly two third of deaths occurred during the first months of life. Thus, close monitoring and supporting reproductive age mothers to increase the uptakes of family planning and antenatal care and follow-up is highly recommended to increase the infant survival. The infant mortality rate is a key population health indicator . A high In 2016, infant mortality contributed to more than 75% of all underfive deaths globally . For theThe risk of a child dying before his first birthday is higher in African region (52 per 1000 live births), over six times higher than that in the European region (8 per 1000 live births) . In AfriEthiopia is among the few regions with the highest burden of IMR. To reverse this, Ethiopia has made large-scale investments in basic healthcare over the last decade; mainly in the disadvantaged rural population –9. AntenThe 2016 Ethiopian Demographic and Health Survey (EDHS) result showed that the infant mortality rate for the 5 years before the survey is 48 deaths per 1000 live births. The survey’s results showed that infant mortality declined from 97 deaths per 1000 live births in 2000 to 48 deaths per 1000 live births in 2016, which accounts for a 50% reduction in the last 16 years. Among those infants that do not survive, about 72% deaths occur before the first birthday [https://dhsprogram.com/data/available-datasets.cfm. The 2016 EDHS sample was selected in two stages. In the first stage, the total of 645 clusters  were randomly selected proportional to the household size from the sampling strata and in the second stage, 28 households per cluster were selected using systematic random sampling.The data set used in this study was obtained from the Ethiopian Demographic and Health Survey conducted in 2016, which is the fourth comprehensive survey. It was a population-based cross-sectional study conducted from January 18, 2016 to June 27, 2016, across the country and it is available from the MEASURE DHS database at Representative samples of 18,008 households were selected and 16, 650 households were interviewed in 2016 EDHS. For individual interview, 16, 583 eligible women were identified from the interviewed household. A total of 15,683 women aged 15–49 interviews were completed [In this study, the major outcome variable was time to infant death, measured in months between birth and the first birthday within the preceding 5 years of the survey. In this finding, those infants who died between birth and the first birthday were events and those who were still alive and did not reach their first birthday were considered as censored. Death was considered as the death of infant during the 5 years preceding the survey due to any cause.The predictor variables were categorized into three  based on Mosley and Chen 1984) theoretical framework showed as in Fig. 984 theorp-value < 0.25 in the univariate Cox regression analysis were included in the multivariate analysis. We estimated hazard ratios and their 95% confidence intervals. In the multivariate analysis, we used p < 0.05 as threshold for statistical significance.We used Cox regression model in the survival analysis, statistical analyses were performed using STATA version 14. Cox regression model is the most popular regression techniques for survival analysis because it examines the impact of various predictors of the risk of death. The additional advantage of this model is that it accounts for censoring in the data , 13. VarP = 0.0137). Variables with missing/don’t know category were excluded from analysis. Accordingly, the rate of missing data for the three variables was below 2%.Infant mortality rates were calculated by summing up the number of infant deaths during infancy period divided by the total number of months of follow-up during the study period. Performing log-log survival curves based on Schoenfeld residuals was used to assess the proportional hazard assumption. Accordingly, the model fitness statistics was significant  using infant months of observation.A total of 10, 641 live births born during the 5 years preceding the survey and who had a full 1 year follow-up time were included into this analysis. The male to female sex composition at birth was nearly the same and the great majorities (96%) were single births , ). The difference in survival probability between male and female infants was statistically significant. Among the infants who failed to survive up to their first years of age (4.8%), nearly two-third (65%) had died during the first months of life , the estimated hazard ratios for mothers who had secondary and higher education were 0.68 (95% CI: 0.56–0.98) and 0.51  respectively. The risk of death was lower by 32 and 49% for infants born from mothers who had secondary and higher education respectively, compared with infants born from non-educated mothers  and for longer than 47 months was 0.51 (95% CI: 0.27–0.92) compared to birth interval between 24 and 47 months (reference category). The risk of death of infants with a preceding birth interval shorter than 24 months was 2.11 times higher and for longer than 47 months reduced the risk of death of infants by 49% compared to the reference category (Table P = 0.0137).The estimated hazard ratio for multiple births in relation to singleton was 4.07(95%CI:1.14–14.5). The risk of death for multiple births was 4.07 times higher than singleton. With regard to average size infants, the estimated hazard ratios for very small size infants and smaller than average size infants were 3.74 (95% CI: 1.73–8.12) and 3.23 (95% CI: 1.40–7.41) respectively. The risk of infant death for very small size and smaller than the average size were higher by 3.74 and 3.23 times compared to the average size of infants. Similarly size at birth was significantly associated with infant mortality  compared to the reference category. Another study conducted in Ethiopia  suggesteThis study also demonstrated that, the risk of death of infant was higher among multiple births than singleton. A previous study conducted using the EDHS 2011  suggestep < 0.001). A study in Global infant mortality trends and attributable determinants – an ecological study using data from 192 countries for the period 1990–2011 [With regard to birth interval, the risk of infant mortality was higher for infants with a preceding birth interval shorter than 24 months and lower with preceding birth interval longer than 47 months. The mean estimate of survival time for infants who were born within less than 24 months was 6.2  months, whereas for infants born above 47 months of preceding birth interval, it was 5.5  months. The difference in time between the two categories of infants was statistically significant  during the earlier periods of infancy is highly recommended. Moreover, mothers with multiple birth, giving birth to a child with birth interval of below 2 years and infants born with smaller than average size at birth deserve special attention.


Based on first-principles calculations, the effects of an external electric field (E) applied along the [111] direction of the orthorhombic perovskite, CH3NH3PbI3, on its electronic structure and optical properties are investigated. Our results indicate that the electric field strength affects the band gap (Eg) of CH3NH3PbI3 . The energy difference between the two peaks closest to the Fermi level in the density of states diagram decreases with increasing applied electric field strength along the [111] direction, indicating that the covalent character increases between A-sites cations and I-sites anions. Both the cell volume and the final energy show the same increasing trend. The absorption peaks move toward the visible-frequency range, with the optimal band gap of 1.1–1.45 eV and E = 0.04–0.06 eV/Å/e. In particular, the non-linear change of the second-order Stark effect causes a non-linear change in the band gap.The organic-inorganic perovskite CH In addition, its synthesis is relatively straightforward and can be achieved by simple layer deposition6. Although great success has been achieved in improving the photovoltaic energy conversion efficiency of this perovskite7, perovskites are ideal because they absorb most of the solar spectrum, from the ultraviolet region to the near-infrared region, generate more excitons as more photons absorbed, and bring the energy levels closer to that of the electron transport layer (ETL) or hole transport layer (HTL). The optimal band gap for a single junction solar cell is between 1.1 and 1.4 eV9. However, CH3NH3PbI3 has a narrow direct band gap energy (Eg) of 1.51 eV, which is not optimal and hinders its application.The organic-inorganic hybrid perovskite CHet al.10 investigated tetragonal APbI3 perovskites with A = Cs+, (CH3NH3)+, and (NH2)2CH+ and found that CH3NH3PbI3 and (NH2)2CHPbI3 have the same band gap. Hao et al.11 studied the performance of CH3NH3Snx1−PbxI3 perovskite solar cells. Their results indicated that the band gaps of mixed Pb/Sn hybrid perovskites have two extremes, 1.55 and 1.35 eV, depending on the ratio of Pb to Sn, but the band gaps were narrow (<1.3 eV). Furthermore, a band gap of 1.60 eV for CH3NH3PbI312, 2.39 eV for CH3NH3PbBr3, and 3.17 eV for CH3NH3PbCl314 was obtained. Moreover, it was shown that the optical band gap can be tuned from a direct band gap of 1.52 eV to an indirect band gap of 2.64 eV by varying the CH3NH3I concentration15. In addition, the band gap of the tetragonal phase of CH3NH3PbI3 decreased with decreasing temperature16, following the relationship Eg (T) = Eg (T0) − b.kB.(T0 − T)2. Thus, finding the optimal band structure remains an important physical problem.Using first-principles calculations, Amat et al.17 reported the influence of external electric fields on the electronic structure and optical properties of TiO2. They found that the band gap of TiO2 becomes narrower with increasing electric field strength, decreasing to 0 eV when the electric field is 0.25 eV. Varignon et al.18 used an electric field to control the Jahn-Teller distortions in bulk perovskites such as SrTiO3, BaMnO3, YMnO3, and BiFeO3. Bellaiche et al. reported that an external electric field could induce polarization paths in PbZrx1−TixO3 perovskites and lead to the expected sequence of tetragonal, A-type monoclinic, and rhombohedral structures19. Xu et al.20 demonstrated that electric fields could induce a change from a ferroelectric phase to an antiferroelectric phase in a lead-free NaNbO3-based polycrystalline ceramic. Therefore, it is very important and valuable to investigate the relationship between external electric fields and the physical properties of the organic-inorganic hybrid perovskite CH3NH3PbI3. CH3NH3PbI3 undergoes two phase transitions, one at 160 K  and the other at 330 K 21. Using Density functional theory (DFT) calculations, Leppert et al. investigated the Rashba effect induced by the electric field and strained in the hybrid halide perovskite CH3NH3PbI3 with a tetragonal and cubic structure22. Although the orthorhombic phase is realized with rotations about the C–N axis that freeze out when T ≤ 162 K, temperature is not the only factor affecting these properties. An external electric field or magnetic field could also be an important factor, so we chose the orthorhombic CH3NH3PbI3 as our subject to investigate these effects.In many cases, the electric field effect can change the geometric, electronic, magnetic, and band structures of materials, and thus regulate their physical properties. Zhao 3NH3PbI3. This study provides a method for obtaining the optimal band gap of CH3NH3PbI3 and expands the scope of its applications.In this article, we investigate the effects of an external electric field applied along the [111] direction on the geometry structure, electronic energy band structure, total density of states, and optical properties of CHE) direction, including the [001], [010], [100], [110], and [111] directions, on the band structure of CH3NH3PbI3 were studied. The application of an electric field along the [111] direction in CH3NH3PbI3 decreases the band gap, while fields aligned along the other directions increase the band gap. Therefore, we only investigated the physical properties of CH3NH3PbI3 under an electric field aligned along the [111] direction to obtain the optimal band gap of 1.1–1.4 eV.The effects of the external electric field  functional developed by Perdew, Burke, and Ernzerhof PBE23 and PBEsol24, which are similar to the results25 reported by Menéndez-Proupin et al. The detailed calculation methods were shown in the Method section. It should be noted that the number of conduction bands calculated using GGA + PBEsol is greater than that calculated using GGA + PBE. In the presence of an applied external electric field with a strength ranging from 0.01 to 0.06 eV/Å/e, the band structures of the orthorhombic CH3NH3PbI3 are similar. Figure E = 0.06 eV/Å/e. The conduction band shifts downward to the Fermi level (0 eV) and the energy band near the CBM is more dispersed, resulting in a change in the band gaps. All the configurations indicate an indirect band gap semiconductor, and the VBM and CBM are located at the centre of the Γ-point in k space. Because of the narrower indirect band gap of the CH3NH3PbI3 semiconductor, only a small amount of energy is required for the formation of excitons. However, the GGA + PBE and GGA + PBEsol methods underestimate the band gap because of self-interaction errors, suggesting that the actual band gap of CH3NH3PbI3 is slightly smaller than the calculated values.The band structure of CH3NH3PbI3 are strongly affected by the applied electrical field strength. As the external electric field strength increases, the band gaps calculated by GGA + PBE first decrease linearly, then increase slightly, and finally, decrease linearly. The band gaps calculated by GGA + PBEsol indicated the optimal value between 1.1 and 1.4 eV for all the structures under an external electric field, as shown in Fig. The band gaps of CH3NH3PbI3 in the presence of an external electric field (E = 0.00–0.06 eV/Å/e). As the external electric field increases, (i) the two peaks corresponding to orbital energies from −22.5 to −15 eV gradually broaden and then become narrow, reaching their maximum widths when E = 0.03 eV/Å/e. (ii) The five peaks corresponding to orbital energies between −15 and −5.5 eV gradually broaden. (iii) Parts of the TDOS of the orbitals crossing the Fermi level increase with increasing external electric field, suggesting that the band gap of CH3NH3PbI3 decreases. (iv) The CBM gradually narrows and shifts to the Fermi level, which also decreases the band gap, suggesting a pseudo-energy gap decrease, while the strength of the covalent character increases between the MA-cations and I anions.Figure 3NH3PbI3 when E = 0.00 and 0.06 eV/Å/e were shown in Fig. E = 0.00, the lost average H cations have three kinds including 0.34, 0.22, and 0.21 electrons, the lost average Pb cations have one kind with 0.88 electrons, the gain anions with C and N have 0.61 and 0.70 electrons, and the gain I anion have two kinds including 0.36 and 0.52 electrons. For the E = 0.06 eV/Å/e, the lost average H cations have seven kinds including 0.15, 0.16, 0.29, 0.30, 0.34, 0.35 and 0.44 electrons, the lost average Pb cations have one kind with 0.54 electrons, the gain C anions have 0.65 electrons, the gain N anions have two kinds including 0.77 and 0.76 electrons, and the gain I anion have six kinds including 0.29, 0.37, 0.38, 0.39, 0.40, and 0.41 electrons.The electron densities of CH3NH3PbI3 (GGA + PBEsol) under applied external electric field strengths of E = 0.00 and 0.06 eV/Å/e. The electronic orbitals 5d6s6p, 5s5p, 2s2p, 2s2p, and 1s are modeled as the valence orbitals for Pb, I, C, N, and H, respectively. The s-p hybrid level increases with external electric field increasing, and the effect on the conduction band is much more pronounced than that on the valance band. The peak near the orbital energy level at −5.0 eV splits into two peaks, which is attributed to the Stark effect of the s and p electrons, and one peak position shifts to the Fermi level. The external electric field causes the d electrons of Pb to shift to higher energies, but the d electrons do not affect the s and p electrons.Figure E increases. The physical mechanisms underlying the change in the band structure of CH3NH3PbI3 is ascribed to the C-N and Pb-I bond lengths, changes in the lattice structure, and charge transfer between the Pb and I atoms. The lattice distortion caused by the mutation of lattice parameters may lead to change in the microscopic electric structure, band structure, and density of states, similar to the results reported in ref.17.The Stark effect can induce the splitting of degenerate energy levels. The degree of the band splitting increases with the electric field, and a smaller band gap can be obtained. All peaks of the orbital energy level in the DOS curves broaden and shift to lower energies as a, b, and c), cell volume (V), bond length (d), and final energies  are listed in Table EFinal (E) = 1591.989E – 12504.565 and V (E) = 1035.804E + 983.666. In addition, the bond distances, including the d(C-N) and d(I-Pb) distances, increase monotonously with increasing E, which leads to weak interactions between C and N as well as between I and Pb. To illustrate the extent of lattice distortion, two parameters . The Pb-N-C angle decreases with increasing external electric field, which consistents with the increase in the lattice parameters and cell volume.In addition, the orientation of the CH3NH3PbI3 may show different preferential growth directions with different substrates, so obtaining the optical performance in this growth direction is an important physical problem. Let us take the [100] direction as the preferred growth direction as an example to illustrate this problem. Figure 3NH3PbI3 in the presence of an external electric field. It is seen that the electric field significantly influences the optical absorption characteristics of CH3NH3PbI3. We assume the highest intensity absorption peak as the main absorption peak. The values 5.5 eV and 3.68 eV in the range of 0~5 eV for CH3NH3PbI3 calculated by the GGA + PBE and GGA + PBEsol methods are the positions of the main absorption peak without the external electric field, which corresponds to absorbed light with the highest frequency. As the external electric field increases, the peak positions shift to lower frequencies, approaching the visible light region, and full width at half maximum (FWHM) of the absorption peaks decreases, which makes light absorption more effective and thus improves the photoelectric conversion. In addition, there are some absorption peaks at higher energies beyond the visible range, which do not play a major role in photoelectric conversion, but can become a candidate as optical detection device such as ultraviolet band.CHEg and wavelength should satisfy the following relation:As the first-order approximation, the band gap (i)E ≤ 0.03 eV/Å/e, ν and ν100 decrease with an increase in the external electric field; when E ≥ 0.04 eV/Å/e, ν and ν100 increase with external electric field increasing, except ν with 0.04 eV/Å/e based on the GGA + PBE. Here, ν is the frequency calculated by the band gap, ν100 is the frequency along the [100] direction based on the Fig. The band gap decreases non-linearly with increasing external electric field. When (ii)Eg) based on the band structure is similar to Eg’ based on the optical properties. Based on adiabatic approximation and single electron approximation, the relationship between absorption coefficient and photon energy can be expressed as,The band gap  will change to the initial values (E(0)i) by an amount ∆Ei.Here, ∆Ei can be expanded with the additional energy of the electric field, which are Stark effect orders denoted as first order ∆E(1)i or second order ∆E(2)i.i | is the initial state of the system, then we have,The energy changes owing to the electric field, where <ψFor second-order energy changes, the summation is over all possible states of the system, so,E can be considered a constant over the perturbation volume,If − anions are coupled to the movements of the monovalent MA+ cations and the rotation of the MA dipoles. This change in polarizability in the domains can influence the second-order Stark effect through the change in the dielectric constant owing to the change in the optical absorption spectrum28. Then, ΔE(2) may reflect in two possible first-order Stark effects, as shown in Fig. ΔE(2) is positive, the band gap will widen; if the value of ΔE(2) is negative, the band gap will shrink. However, the second-order Stark effect cannot be larger than the first-order Stark effect, so CH3NH3PbI3 without an external electric field has the maximum band gap. The non-linear extent of the second-order Stark effect cause a non-linear change in the band gap.From Table 2 as ETL layer must be lower than CBM of perovskite active layer. (ii) The Lowest Unoccupied Molecular Orbital (LUMO) of spiro-omeTAD as HTL layer must be higher than VBM of perovskite active layer. The external electric field induced the Stark effect, splitting energy levels for TiO2 and spiro-omeTAD  The Highest Occupied Molecular Orbital (HOMO) of TiO3 structure can be applied to solar panels in space with lower temperature. Due to cosmic microwave background with 3 K29, the perovskite solar cells with orthorhombic phase can accomplish as Power generation device candidate in space such as International Space Station, satellite, space shuttle, spacecraft, lunar rover vehicle, etc. Moreover, this may provide a new idea to control the properties of the tetragonal structure at room temperature.As a preliminary exploration, we believe that this study is valuable. Indeed, the calculated results are aimed for the orthorhombic structure and not the tetragonal structure at room temperature, but the orthorhombic MAPbI3NH3PbI3 is temperature, and the external electric field causes the Stark effect splitting energy level of C, N, H, Pb and I, and the two structures with the same element and the similar chemical bond characters. Thus, we inferred that the Stark effect for CH3NH3PbI3 with a tetragonal structure may be observed at room temperature.The main reason for the orthorhombic to tetragonal transition in CHet al.30. It noted that the device in this study only provide the external electric field, do not provide electrons. The large DC voltage near 100 V can be obtained by DC boost circuit, which can resolve the electric field strength. The positive electrode is connected with the transparent ITO for visible light, and the negative electrode is connected with Au; the directions of the two electrodes can control the direction of the electric field, including the [111] direction. Moreover, the distance between the positive and negative electrodes, as well as the insulation thickness and dielectric constant, influenced the electric field strength.The device for realizing the external electric field is shown in Fig. et al. used an external magnetic field to adjust the relative energy levels between a skyrmion and a ferromagnet globally, and obtained an electric field of 1 V/nm, which corresponds to a magnetic field of about 40 mT for their system31. Qin et al. applied an external electric field to drive the ultra-low thermal conductivity of silicene. Using an electric field (Ez = 5 V/nm), the lattice thermal conductivity of silicene can be reduce a record low value of 0.091 Wm−1 K−1, which is comparable to that of the best thermal insulation materials32. The main problem caused by the huge electric field may be the device breakdown, which is attributed to the self-sustainable discharge for uniform electric field. The more uniform the electric field is, the higher the self-sustainable discharge voltage is. So the transparent ITO as the positive electrode and the Au film as the negative electrode should possess the rule shapes and flat surfaces, which would decrease the degree of dielectric polarization, and reduce the possibility of the tip discharge.It noted that the external electric field of about 0.06 eV/Å/e is large, which is equal to 0.6 V/nm, but this external electric field can be carried out in practice. For example, Hsu 3NH3PbI3 under an external electric field aligned along the [111] direction. The external electric field increases the lattice parameters and the cell volume, stretching the c-axis and influencing the degree of lattice distortion. The external electric field controls the band gap from 1.70 to 1.073 eV, corresponding to external electric field strengths of 0.00 to 0.06 eV/Å/e. The rotation of the MA dipoles induced a second-order Stark effect, and the non-linear change in the second-order Stark effect causes a non-linear change in the band gap. In addition, the absorption peaks and the peak locations are affected by the external electric field. Thus, this study provides a possible method to improve the photoelectric conversion of perovskite solar cells.In conclusion, we have used first-principles calculations to calculate the geometries, band structure, electronic properties, and optical absorption properties of perovskite CH3NH3PbI3 perovskite undergoes two phase transitions, one at 160 K  and the other at 330 K . The orthorhombic CH3NH3PbI3 structure could be closer to that at the 0 K, so we chose this as the research object given the DFT calculations are performed at 0 K. Based on the structure reported by Menéndez-Proupin et al.25, CH3NH3PbI3 perovskite has an orthorhombic crystal structure in the space group Pnma (no. 62), with lattice parameters of a = 8.8273 Å, b = 12.6793 Å, and c = 8.5099 Å, as shown in Table 3NH3PbI3 has a typical AMX3 perovskite structure with the unit cell consisting of a central lead atom octahedrally coordinated to six iodide atoms. The PbI6 octahedron is located inside a cube with each iodide at the centre of a cubic face, and the CH3NH3 cations are positioned at the corners of the cube. To study the effect of the electric field on the physical properties of CH3NH3PbI3, the external electric field along different directions  was investigated.CH3NH3PbI3 exposed to different external electric fields using the Cambridge Serial Total Energy Package (CASTEP)34 program. The generalized gradient approximation (GGA) functional developed by Perdew, Burke, and Ernzerhof 24 was used. These exchange-correlation functionals employed were same as those in the study of the self-regulation mechanism for charged point defects in hybrid halide perovskites reported by Walsh et al.35. The spin-orbit coupling (SOC) effect is reported to have little influence on the geometric structures36. Ultra-soft pseudopotentials with a cutoff energy of 310 eV (based on test results) were used to describe the interactions between the valence electrons and the ionic core, and including relativistic effects for Pb and I atoms. A 3 × 2 × 3 Monkhorst-Pack k-point scheme was used to calculate the absorption spectra. We performed the convergence test, and found the results with 500 eV cutoff energy and 5 × 5 × 5 Monkhorst-Pack k-point scheme to be similar to those with the above parameters. The convergence tolerances for geometry optimization calculations were set to a maximum displacement of 5.0 × 10−4Å, maximum force of 0.01 eV/Å, maximum energy change of 5.0 × 10−6 eV/atom, maximum stress of 0.02 GPa.We calculated the physical properties including the energy band, the density of states (DOS), and optical absorption in the orthorhombic perovskite CH35, PBEsol as exchange–correlation functional is a revision of the PBE functional, which improves equilibrium properties of densely-packed solids and their surfaces, specifically tailored for solids. It has been shown to yield structural data in accordance with experiment reported by F. Brivio et al.37. This functional predicts the structure of common London-dispersion corrected functions without the addition of an empirical potential.According to the refs