Background: The global burden of stillbirth and neonatal deaths remains a challenge in low-income countries. Training in neonatal resuscitation can reduce intrapartum stillbirth and early neonatal mortality. Previous results demonstrate that infants who previously would have been registered as stillbirths are successfully resuscitated after such training, suggesting that there is a process of selection for resuscitation that needs to be explored.Objective: To compare neonatal resuscitation of low birth weight and normal birth weight infants born at a facility in a low-income setting.Methods: Motion-triggered video cameras were installed above the resuscitation tables at a maternity health facility during an intervention study (ISRCTN97846009) employing the Helping Babies Breathe resuscitation protocol in Kathmandu, Nepal. Recordings were analysed, noting crying, stimulation, ventilation, suctioning and oxygen administration during resuscitation. Birth weight, Apgar scores and sex of the infant were retrieved from matched hospital registers. The results were analysed by chi-square and logistic regression.Results: A total of 2253 resuscitation cases were recorded. Low birth weight infants in need of resuscitation had higher odds of receiving ventilation  and lower odds of receiving suctioning  after adjustment for the Helping Babies Breathe intervention, sex of the infant and place of resuscitation within the facility. The rates of stimulation and administration of oxygen were the same in both groups.Conclusions: Low birth weight was associated with more ventilation and less suctioning during neonatal resuscitation in a low-income setting. As ventilation is the most important intervention when the infant does not initiate breathing after birth, low birth weight was not a predictor for the decision to withhold resuscitation. Frequent routine use of suctioning of the lower airways continues to be a problem in the studied context, even after the introduction of the Helping Babies Breathe protocol. Of the 5.8 million children who die before their fifth birthday each year, 2.9 million die during the neonatal period . In addiThe clinical adherence to the steps in resuscitation protocols varies considerably and is a major challenge, especially in low-income contexts . Video-rPremature or small-for-gestational age (SGA) infants are generally of low birth weight (LBW) and those infants clearly run a higher risk of mortality and morbidity than normal birth weight (NBW) infants . LBW is Paropakar Maternity and Women’s Hospital (PMWH) is a tertiary government hospital in Kathmandu, Nepal, providing gynaecologic, obstetric and newborn services. In 2012 there were approximately 22,000 deliveries at the facility with a stillbirth rate of 19 and an early neonatal mortality rate of 9 per 1000 live births .The STROBE  checklist was used to address the methodology used in this paper (see the Appendix). Data for this study were generated from a study of the Helping Babies Breathe (HBB) resuscitation protocol performed at the facility between 2012 and 2013  . The basDeliveries were performed at three wards: Labor Room for complicated deliveries, Newborn Centre for uncomplicated deliveries and the Operations Theatre for caesarean section. Occasionally, women delivered in the admission room. Resuscitation tables were available in each ward to allow for a swift transfer from the mother to the table in cases of apnoeic infants. Motion-triggered charge-coupled device (CCD) cameras (model MTC-505DH) were installed over the resuscitation tables located at the different wards where deliveries took place. Only the infants and the hands of healthcare providers were in the field of vision to ensure the confidentiality of the staff. No sound was recorded. The obtained videos contained time stamps and information of the location within the facility to allow them to be matched with the hospital register of the recorded delivery. If more than one delivery had the same time stamp, the place of delivery or the sex of the infant was used to distinguish them from each other. If matching was not resolved, the video observation was discarded. The video recordings were analysed by members of a surveillance team hired by the research group and the members were not affiliated to the hospital. Those surveillance officers were public health students trained in utilising a data collection tool in order to retrieve data on the initiation of resuscitation measures of stimulation, suction, ventilation and provision of oxygen. It was also noted whether the infant was crying after birth.During the baseline period the inter-rater reliability of the analysed videos was investigated using 50 randomly selected recordings . The evaIn the baseline period, the study protocol regarding the number of cases of infants needing resuscitation to be analysed was reviewed. The process of observing video from all the infants resuscitated turned out to be an unsustainable workload for the surveillance officers to perform. Thus, from November 2012, only videos from the resuscitation of control and case infants were analysed. In this study we therefore used video data from July to October 2012 when all infants on the resuscitation tables were analysed, and from January to September 2013 when only case and control infants were analysed, to represent the baseline and intervention period, respectively.LBW was defined using the WHO definition of less than 2500 grams . At the As 2500 grams represented the cut-off for LBW, this result challenged the distribution between the two groups of infants in our study. This over-registration of infants at 250- or 500-gram multiples is a known source of error for the registration of birth weights called ‘heaping’ . An adju2–test was used for comparing resuscitation measures for LBW and NBW babies during baseline and intervention, respectively. Logistic regression reporting odds ratios (OR) was applied to analyse differences in resuscitation practice between LBW and NBW infants. Birth weight was set as the dependent variable and resuscitation activities as independent variables. Statistical significance was decided at p-values below 0.05. As the HBB intervention was expected to affect the practice of neonatal resuscitation at the facility, we first analysed each period separately and subsequently in one data-set adjusting for the intervention. As we hypothesized that gender could affect the decision to start resuscitation, this variable was adjusted for. Previous findings also indicated that the location of the table within the facility could affect the odds of receiving ventilation, thus we chose to also adjust for the place of delivery within the facility [Pearson’s χfacility .During the whole study period a total of 2253 resuscitations were recorded on video. After the adjustment for heaping, 417 (19%) of those were LBW, and 1836 were NBW infants. The mean birth weights for LBW and NBW infants were 2006 and 3049 grams, respectively. Of the non-crying infants, and thus those assumed to be in need of resuscitation measures, 250 were LBW and 941 NBW infants . Data onThe data on whether the infants were crying from the video material were crosschecked with low Apgar scores at one minute and five minutes. We found that few of the crying infants at both time intervals simultaneously had low Apgar scores, but also many of the non-crying infants did not have Apgar scores below the chosen cut-offs .Table 1.p < 0.01). All other resuscitation interventions of stimulation, suctioning and administration of oxygen were more common during the baseline period (p < 0.05). Suctioning was frequently used and was performed on most non-breathing babies, both before and after the intervention , and higher for ventilation . Estimates did not change significantly when adjusting for gender and place of delivery. There was no difference in the odds of stimulation and administration of oxygen to LBW infants in the baseline period. During the intervention period, both weight groups were treated the same for all measures .Table 2.For the whole study period, odds ratios did not change significantly compared to what was found in the baseline alone. Odds of suctioning of LBW infants were lower , and they were higher for ventilation  after adjustments were made for intervention, gender of the infant and for place of delivery .Table 3.The hypothesis that infants would receive inadequate resuscitation because of LBW was not confirmed. We found that the odds were lower for suctioning of LBW infants, but, as the practice generally is excessively used in this setting, the result rather suggests a more optimal handling of LBW infants. Odds of ventilation were higher in the LBW group, contrary to our hypothesis, as ventilation is the most crucial step to initiate in infants where resuscitation is needed . ResultsThe rate of stimulation of non-breathing infants was reduced after the HBB intervention for the whole study population. One explanation could be that the protocol clearly states the drying of all infants as the first step, followed by a brief stimulation by rubbing the back of the infant if drying does not result in breathing. When observing some of the videos, prolonged and sometimes slightly violent practices of stimulation were present at the facility during the baseline period. As stimulation after the intervention was shorter and health workers moved faster to initiate ventilation, the observers did not note the shorter periods of stimulation as such in the data sheet. The inter-rater reliability of stimulation was also admittedly low in previous studies of the data . CorrectThe usage of suctioning of the lower airways was excessive at the studied facility both before and after the intervention for both weight groups. When observing the video recordings we found that, during the baseline period, a catheter was always used, and suctioning of the lower airways was routine when the intervention was applied. After HBB training, some health workers used the penguin suction devices provided by the HBB package, but catheters were still utilised in many cases where suction was performed. The practice of routine lower airway suctioning dates back many decades to when both intrapartum and post-partum suctioning of neonates seemed logical, especially in the presence of meconium-stained fluids, and studies did not confirm any morbidity correlated to such suctioning . This haOxygen was administered to many infants in our study. Proportions were reduced after the intervention as expected as the HBB protocol does not include oxygen administration. Rather, HBB suggests transfer to more advanced care if the initial steps of stimulation, clearing of airway and ventilation are not sufficient. There is no evidence supporting the notion that a correct titration of oxygen will increase survival when neonatal resuscitation is initiated with room air as opposed to 100% oxygen . Rather,Our study has some limitations. Firstly, we used infants classified as non-crying from the video material as a proxy to define the need for resuscitation, but we cannot be sure how strong this may be as a predictor. When comparing with low Apgar scores, we found that only a few of the babies defined as crying had an Apgar score below the chosen cut-offs, at both one minute and five minutes. However, many infants who were defined as non-crying in the video material also did not have low Apgar scores. Ideally, an evaluation of whether health workers are performing according to guidelines for a particular intervention would include continuous intrapartum foetal heart rate monitoring and early postnatal electrocardiogram. Secondly, we did not have reliable data on the sequence of interventions during resuscitation. For example, a non-crying baby might have responded to stimulation and therefore there was no need for subsequent ventilation. Thirdly, in the available data, the LBW group contained 10 very, and extremely, premature infants who, in this setting, could be considered to have very low odds of survival, which could have affected the actions taken by the health workers. We chose only birth weight to represent immaturity because of the lack of data on gestational age. Low gestational age combined with LBW could have been a more appropriate representation. For comparison, we calculated ORs for the whole study period, excluding infants with extremely low birth weight (< 1000 grams). The findings were similar and we therefore did not present the results in detail. Fourthly, there could have been a Hawthorne effect in the study as the camera might have influenced the steps taken by the health workers . FinallyUsing video to assess adherence to guidelines in neonatal resuscitation in low-income settings is a promising tool for quality improvement. However, it has its limitations, as demonstrated in this study. In large data-sets, using trained staff when analysing video poses a problem with intra- and inter-rater reliability and it is also very time-consuming. Using better-quality video cameras and the addition of sound could potentially solve some of the problems of gathering reliable data for video interpretation. There is also a need to include coverage of the steps taken between birth and the arrival of the newborn at the resuscitation table. Future possibilities, such as using deep-learning software and allowing for a computer protocol to automatically process the resuscitation videos, should also be explored.Low birth weight was associated with higher odds of performing ventilation and lower odds of suctioning when analysing video recordings of non-crying infants resuscitated in a low-income facility setting. Low birth weight does not seem to be a predictor of the decision to withhold resuscitation in this context; however, the video data used did not include decisions taken outside the resuscitation table. The frequent routine use of suctioning of the lower airways is not supported by evidence and needs to be further addressed in resuscitation protocols for low-income settings as its use can cause complications. More robust methods for assessing skills in neonatal resuscitation, including improved video recording and analysis, are needed.


Despite a shift in clinical practice favouring cesarean section for breech presentation, adequate skills are still needed for a safe vaginal breech birth. This case report illustrates the physiological mechanism of vaginal breech birth. The accompanying pictures are a testimony to the “hands‐off” approach and could be used for educational purposes. She notices that Mrs B. is calm and composed. To alleviate labor pains, Mrs B. instinctively adopts the knee‐elbow position. At 7.40 am, when spontaneous rupture of the membranes occurs, meconium‐stained amniotic fluid is noted. At the same time, Mrs B. experiences an unstoppable urge to push. For this reason, the midwife carries out the first vaginal examination. She diagnoses an unexpected frank breech presentation and full dilatation. The fetal condition is fine as assessed by intermittent fetal auscultation. The couple is informed about these findings and the potential obstetric consequences. The option of giving birth in hospital is brought up. Mrs B., however, declines emergency transport to the hospital as she feels that her baby is due any minute. Being aware of the knee‐elbow position of Mrs B., the midwife then makes a swift decision. Following the couple's wishes, she decides to proceed with a vaginal breech birth in the all‐fours position . In eight women (19.5%), assisting maneuvers were deemed necessary. In four women (9.8%), the knee‐elbow position had to be abandoned; these women gave birth in the supine position by means of the classic delivery techniques. Severe perineal injury was reported less often in women who gave birth on all fours (14.6%) when compared to the matched control group of women who gave birth in lithotomy position (58.5%). However, infants had a lower umbilical cord pH : 7.16–7.22) compared with the matched controls . This is indicative of increased prenatal hypoxic stress, albeit clinically irrelevant In this article, we describe a woman with an unexpected frank breech presentation at term diagnosed at home by the attending independent community midwife. At the time of diagnosis, the parturient had full dilatation. The couple was informed immediately about these findings. The option of emergency referral was declined by the mother‐to‐be, because she felt that the baby was due any minute. Intuitively, the midwife made a courageous decision: She decided to proceed with vaginal breech birth on all fours. In fact, the management of the vaginal breech birth at term on the all‐fours maneuver proved to be a simple, safe, and effective strategy for the woman described in this case report. Breech presentation at term occurs in about 3–4% of pregnant women From studies among women whose delivery is complicated by shoulder dystocia, there is considerable scientific evidence that the all‐fours maneuver is effective for the release of the fetal shoulders To accommodate the attending clinician, women who have a breech presentation at term typically give birth in the lithotomy position. The woman described in this article adopted the physiologically advantageous knee‐elbow position for her own comfort while she was not yet aware of the fetal breech presentation. In fact, it does not take much effort to roll over to the knee‐elbow position during labor, as witnessed by personal observation of women whose birth is complicated by shoulder dystocia.Management of vaginal breech birth in the all‐fours position resembles the Bracht maneuver which is used in many Western countries for spontaneous vaginal breech birth in supine or lithotomy position Following the publication of the Term Breech Trial HW: initiated the preparation of this case report for scientific publication; he wrote the first draft of this manuscript. HBS: provided all details of the breech birth and SJ: searched the literature on this subject and contributed substantially to the contents of the final version of this manuscript.Written consent was obtained from the patient for publication of this case report and any accompanying images. A copy of this written consent is available for review.None declared.


Birthweight reflects intrauterine growth and wellbeing and is recognised globally as an indicator of infant, child health and increasingly adult health . A low bOur aim in this paper was to examine the association between being born small and early childhood morbidity estimated using use of health services information for White British and Pakistani origin children aged 0–3 participating in the Born in Bradford (BiB) cohort study. We chose GP prescribing as a marker of morbidity and selected the three most common prescribing categories: analgesics, antibiotics and bronchodilators, where analgesics was the most common category followed by antibiotics and third, bronchodilators. We also considered the number of GP consultations and emergency and elective hospital episodes as further morbidity indicators. We defined being born small in two ways using a cut-off of being born weighing less than 2500 g and also using customised birthweight charts.The BiB study is a prospective birth cohort study that recruited women during pregnancy, full details of the study methodology have been previously reported . To be eThe number of general practice consultations and prescription data were derived from electronic records. Primary care electronic health records were obtained for BiB participants registered with GP surgeries that use the SystmOne platform. SystmOne has 100% coverage in Bradford and high coverage in surrounding areas. Records were extracted when NHS number, surname, date of birth and gender were an exact match in SystmOne. From the full BiB cohort of children, 99.0% were matched to their primary care records. Hospital episode statistics (HES) were obtained from the Health and Social Care Information Centre (HSCIC), matched to participants using the same process. Hospital admissions were categorised as Hospital Emergency (any emergency admission including to accident and emergency or direct to paediatric departments) and Hospital Elective which describes any elective admission either as an outpatient or inpatient (90% were outpatient episodes).Birthweight was obtained from hospital birth records and in all participants was recorded immediately following birth using SECA digital scales. We identified children as being born small using the World Health Organization (WHO) criteria for low birthweight as a weight at birth of below 2500 g. As a low birthweight can be the result of either premature birth or restricted growth in utero and because here we are primarily interested in restricted growth or low term birthweight, we included gestation as a covariable in the analyses of low birthweight (< 2500 g). We separately calculated customised birth weight centiles that take into account gestational age, maternal height, maternal pre-pregnancy or weight at booking, ethnicity, parity and neonatal sex Gardosi 2004) and are recommended by the UK Royal College of Obstetrics and Gynaecology (RCOG) for assessment of birth weight [04 and arEthnicity was self-reported at the mother’s questionnaire interview and based on UK Office of National Statistics guidance details of which have been previously reported . For thehttp://www.ecctis.co.uk/naric/default.aspx): < 5 GCSE equivalent, ≥5 GCSE equivalent, ‘A’ level equivalent, Higher than A-level equivalent, Other qualifications , Don’t know, Foreign Unknown. Don’t know relates to the mother responding “don’t know” during interview. Foreign Unknown relates to a qualification listed in the free text response but no level of qualification is given or the qualification listed cannot be equivalised to one of the above categories. For these analyses, women were categorised as having been educated beyond the age of 18 or not ,university undergraduate courses). Don’t know and Unknown were categorized as not educated beyond the age of 18. Receipt of means tested benefits was based on the mother or her household receiving any of: Income Support, Job Seekers Allowance, Working Tax Credit or Housing Benefit. Housing tenure was categorised according to whether the woman lived in a household where the home was either part-owned (i.e. mortgaged) or owned outright, or not (i.e. rented). Maternal smoking was categorised as never, past (but not during this index pregnancy), current/during the index pregnancy.A priori we considered maternal parity, infant sex, gestational age, maternal age, social economic information  and smoking as characteristics that might confound any associations. Maternal parity, gestational age (to the last completed week) and infant sex were all obtained from obstetric medical records. Customised birthweight charts account for gestation, parity and infant sex therefore these variables were only added to low birthweight analyses. Maternal age, social economic information  and smoking data were obtained from the interviewer administered mother’s questionnaire completed at recruitment. We equivalised the mother’s highest educational qualifications  into one of several categories using UK NARIC . Negative binomial regression models were employed as the outcome measures  were over dispersed and did not fit a Poisson distribution well. Models were constructed for each outcome and used to predict the incidence of GP consultations, number of prescriptions and hospital episodes for children based on their ethnicity, low birthweight and SGA categories: after adjusting for the covariables described above and taking into account individual exposure time (the proportion of the study period that a child is registered with a GP practice using SystemOne). Incidence rate ratios (IRR), the ratio of predicted events for Pakistani children compared to White British children, with 95% confidence intervals (CI) were also derived to aid the substantive interpretation of ethnic differences.Table Being born small whether classified as low birth-weight < 2500 g) or SGA, was generally associated with an increased rate of all outcomes compared to children not born small and this was consistent across both ethnic groups  that may not be indicative of illness however, we expect this to not differ markedly between the two ethnic groups. Over 99% of analgesic prescriptions were paracetamol or paracetamol based and it is possible that some of these prescriptions may have been associated with routine immunization but we were unable to examine this with the data available, however if this is the case we do not expect it would differ markedly between the two groups’. Likewise, Hospital Emergency episodes will include accident related episodes that do not necessarily reflect morbidity, it is possible that these may differ between the two groups but we are not able to examine this further with the data we have available. Children born prematurely might have a greater risk of respiratory illness and wheeze and as such experience greater morbidity in early childhood , howeverThese results suggest that being categorised as small at birth is associated with increased morbidity estimated using health service use information, in early childhood in both White British and Pakistani origin UK children. This combined with evidence that birthweight is inversely associated with neonatal mortality, educational achievement and adult disease risk –6, highlAdditional file 1:Table S1. Comparison of models of predicted child outcome measures (with 95% CI), by ethnicity, low birth-weight and small for gestational age (SGA-GROW) with and without adjustment for socio-economic variables (predicted rates with 95% CI). Table S2. Comparison of adjusted* incidence rate ratios (95% CI) of child outcome measures by ethnicity, low birth-weight and small for gestational age (SGA-GROW) with and without adjustment for socioeconomic variables. (DOC 89 kb)


Dermoid cysts of the floor of the mouth are rare lesions thought to be caused by entrapment of germinal epithelium during the closure of the mandibular and hyoid branchial arches. They usually present as a nonpainful swelling. This type of lesion occurs more frequently in patients between 15 and 35 years, but can be seen in all age ranges. Histologically, all dermoids are lined by epidermis. The contents of the cyst lining determine the histological categories of the cyst: epidermoid, if epidermis is lining the cyst; dermoid, if skin annexes exist; or teratoid, if there are tissues derivated from the three germinal layers. Anatomical classification is useful for surgical approach choice, intra- or extraorally. This report presents a case of a dermoid cyst of the floor of the mouth in a 12-year-old patient, and a review of all steps necessary for its diagnosis and treatment was made.


To analyze the effect of birth weight on ocular morphology, refraction and visual function in early adolescents aged 12–15 years.0 and J45, corneal power and corneal astigmatism were evaluated for an association with birth weight. Linear and logistic regression with adjustment for age, sex, ethnicity, survey cycle and birth weight as independent variable were calculated.We conducted a secondary data analysis using the public use files from the National Health and Nutrition Examination Survey of the period from 1999 to 2008. Study participants aged 12 to 15 years were included with data on birth weight and ophthalmic parameters including presenting distance visual acuity, objective refraction and keratometry. Visual acuity, sphere, astigmatism in power vectors J0-vector and J45-vector of astigmatism, corneal J0- or corneal J45-vector with birth weight.Linear regression analysis revealed an association between corneal power and birth weight  in the univariate analysis, and in the model adjusted for age, sex, ethnicity and NHANES survey cycle . A lower birth weight was associated with higher corneal power. We found no evidence for an association of visual acuity, sphere, spherical equivalent, JOur data demonstrate that low BW is linked to alterations in keratometric power even in early adolescents aged 12–15 years whereas visual acuity and refractive error showed no association. In recent years, newborns with low birth weight have increased chances to survive. Especially low birth weight is an important parameter indicating prenatal growth restriction. Furthermore, it is assumed that growth restriction during organ development can affect organ morphology and functioning including ocular development and morphology in childhood. For former preterm and/or very low birth weight infants have an increased risk described for reduced visual acuity, higher rNevertheless, existing data mainly relies on examinations in early infancy. It is less clear whether altered ocular morphology in low birth weight infants lasts until adolescents or even until adulthood. Some authors hypothesized that differences in ocular morphology diminish between former preterm low birth weight infants and former full term neonates in the first seven years of life.In addition, former analyses were mainly based on case-control studies or hospital-based studies including infants with extremely low birth weight and controls. It is unclear whether these findings can be generalized to the general population. Consequently, it is of clinical importance to clarify and quantify the influence of this maturity parameter on ocular outcome in a population-based investigation to targeted clinical follow up beyond infancy.Therefore, the purpose of this investigation was to analyze the long-term effects of low birth weight on visual acuity and ocular morphology in early teenage (12–15 years). Our hypothesis was that we would confirm previous findings in a population-based setup, namely an association between low birth weight and lower visual acuity, higher refractive error, higher astigmatism and higher corneal power even in early teenage.https://www.cdc.gov/nchs/nhanes/index.htm, last accessed 2017-05-10). Since 1999, data is collected continuously in two-year periods. Approximately 5000 persons from 15 areas are examined annually. Data is collected via questionnaire-based personal interviews at the participant’s home and a subsequent visit of a mobile examination center (MEC). From 1999 to 2008, NHANES included questions about birth weight as well as an ophthalmic examination. Our analyses are based on the NHANES public use files of these survey cycles .The National Health and Nutrition Examination Survey (NHANES) is a representative survey research program to assess the health and nutritional status of adults and children in the United States of America (Birth weight was collected via the NHANES Early Childhood Questionnaire (ECQ) which surveyed participants up to 15 years of age and asked their responsible adult for health-related data including birth weight in pounds and ounces.During the subsequent visit at the mobile examination center, participants aged 12 years or older were asked to participate in an examination of visual function. Presenting distance visual acuity, objective refraction and corneal radius  were examined using an autorefractor/keratometer  in non-cycloplegic state and taking the average of three measurements. Corneal radius was converted into corneal power using the keratometer index of r = 1.3375. Presenting distance visual acuity was tested in both eyes. This examination was conducted with participants’s own spectacle correction, if available. Objective refraction  and keratometry data  were obtained in a non-cycloplegic state by taking the average of three measurements.To be able to analyze the association between birth weight and ophthalmic parameters, we included study participants aged 12 to 15 years who had had both, data on birth weight and an ophthalmic examination.Age and sex were reported by parents, as was ethnicity. Ethnicity was provided in the categories Mexican American, other Hispanic, Non-Hispanic white, Non-Hispanic black, and other.Exclusion criteria of the analysis were missing proxy-reported birth weight information or a lack of data of the ophthalmic examination. Furthermore, we excluded all negative measurements of corneal power and extreme values of corneal power above 10 diopters.We calculated birth weight in the metric system (grams) from the reported weight at birth in pounds and ounces and categorized the participants in born with low birth weight (<2500 g), high birth weight (>4100 g), and normal birth weight, as specified in the questionnaire. We only included right eyes in our analysis. Spherical equivalent (SE) was calculated as sphere value plus half the cylindrical power. For visual acuity, we transformed the Snellen equivalent to LogMAR. The cate0 and J45 for both refractive and corneal astigmatism as follows: J0 = —C/2 * cos (2α) and J45 = —C/2 * sin (2α); α is the cylindrical axis, and C is the cylinder power. J0 represents the power vector matching the cylinder power of the vertical (90°) and horizontal (180°) meridians. Positive values correspond to with-the-rule astigmatism, negative values correspond to against-the-rule astigmatism. J45 is the power vector corresponding to the cylinder power of the oblique meridians (45° and 135°).Following the approach of Thibos, who applWe used mean and standard deviation to describe the distribution of continuous variables which showed an approximately normal distribution. Absolute and relative frequencies were used to describe categorical variables.For continuous variables of interest, we used weighted linear regression models, and for categorical data we conducted weighted logistic regression analyses.0-vector and J45-vector of astigmatism, corneal power, corneal J0- and corneal J45-vector) with birth weight as independent variable. Multivariable regression models included age, sex, ethnicity and NHANES survey cycle. For visual acuity, we additionally adjusted for wearing distance glasses or contact lenses.As univariate analysis, one model was built for each of the following outcome variable .To account for the complex survey design, we followed the advice of the NHANES analytical guidelines and used combined sample weights for the analyses. The variWe included 4801 NHANES participants of the survey cycles 1999–2008 with available information on birth weight and an ophthalmic examination. For corneal power we excluded negative values (n = 48) and extreme values above 10 diopters (n = 5), as they are highly suspected to be measurement or data entry errors.Age at examination of the study sample was 13.98 +/- 1.16 years and 51% were female. 34% were Mexican Americans, 5% other Hispanics, 27% non-Hispanic Whites and 31% non-Hispanics Blacks, 4% had another ethnicity. The mean birth weight was 3298 +/- 654 g, 461 (10%) persons had a birth weight below 2500g and 400 (8%) persons had a birth weight over 4100g. Data of general and ocular parameters with stratification on birth weight are reported in 0-vector and J45-vector of astigmatism, corneal J0- and corneal J45-vector were not associated to birth weight in the respective models  in the univariate analysis , and in e models .0-vector showed an association to high birth weight in the multivariable regression model.With respect to birth weight groups, a 0.70 diopters higher corneal power was associated to birth weight below 2500g compared to normal birth weight (2500-4100g) in the multivariable linear regression model p<0.001; . A birth45-vector of astigmatism were not linked to birth weight, while J0-vector of astigmatism was associated  had an astigmatism of at least 2 diopters. AdditionIn our analysis we found an association between higher corneal power and low birth weight in in early adolescents aged 12 to 15 years. In former preterm and low birth weight infants a smaller corneal radius was observed compared to full term infants from birth up to early childhood., 19, 20 Other corneal properties, such as central corneal thickness seem to be linked to birth weight as well. Some authors reported thicker central corneal thickness in preterm newborns in comparison to full term newborns., 25 OtheThe strength of the NHANES study lies in the standardized population-based study design and the large sample size. Furthermore, the adjustment for different covariates contributes to precise estimates. Several studies detected a high reliability of mother reported birth weight as proxy-reported birth weight parameter.–32 BecauOverall, this study presents the results of a population-based study of early adolescents aged 12 to 15 years and reports the relationship between birth weight and visual acuity, refractive error, astigmatism, and corneal power. Our results highlight that low birth weight has an impact on corneal configuration even after the first decade of life. Namely corneal power is higher in early adolescents with low birth weight. Due to the inverse correlation between corneal power and corneal curvature this study underlines that low birth weight seems to lead to a less flattening of corneal curvature which persist until early adolescence. Furthermore, the lack of association between birth weight and visual acuity and refractive error could indicate these effects may be limited to infancy and childhood and are not present in early adolescence anymore in a population-based approach.S1 TableLegend: Results from the multivariable linear regression models adjusted for age, sex, ethnicity and NHANES examination cycle. Reference was the normal birth weight group (> = 2500 g—< = 4100g). Myopia was defined as spherical equivalent below -0.5 dioptres.(DOCX)Click here for additional data file.S2 TableLegend: Results from the multivariable linear regression models adjusted for age, sex, ethnicity and NHANES examination cycle. Myopia was defined as spherical equivalent below -0.5 dioptres.(DOCX)Click here for additional data file.


The Three Delays Model has proven a useful framework for examining barriers to seeking obstetric care and preventing maternal and child mortality. This article demonstrates the applicability of the Three Delays Model to the case of civil registration in rural Indonesia and examines ways that efforts to strengthen civil registration services can draw on lessons from maternal and child health programming. Twenty focus group discussions were conducted using a participatory ranking exercise in four Indonesian districts. Focus groups were stratified into four groups: (1) government officials involved in civil registration, (2) civil society organization members that assist communities in civil registration, and (3) female and (4) male community members. Transcripts were analyzed using constant comparative method and thematic analysis, revealing barriers that communities commonly faced in accessing civil registration services. In examining the categories and themes related to these barriers, the research team found a significant overlap with the factors and phases of the Three Delays Model. Participants were delayed from seeking registration services by a range of sociocultural factors and by the perceived inaccessibility and poor quality of services. Once they decided to seek care, long distances to services and poor transportation options delayed their access to registration offices. Finally, a series of bottlenecks in service provision created extended delays once applicants reached registration offices. Ownership of civil registration documents in Indonesia remains exceptionally low, with just over half of children and youth possessing a birth certificate. To strengthen civil registration and health systems more generally, it is important to understand the factors that enable and constrain civil registration, how these factors relate to one another, and how they change over a child’s life. Around the world, nearly one in three children under the age of five do not have a birth certificate . ResearcAddressing these inequities in civil registration is a key component of the Indonesian government’s Medium Term Development Plan, which aims to increase birth certificate coverage to 85 percent of all children under 18 years old by 2019, with a specific focus on vulnerable populations . AccordiIn addition to being a development priority, strengthening civil registration is increasingly seen as a core investment in public health as well . Civil rWith the Indonesian government’s renewed commitments to improving civil registration and maternal and child health under its National Medium Term Development Plan and the Sustainable Development Goals (SDGs), locating birth registration within a healthcare framework can help to reinterpret the challenges the country faces and can inform new strategies that strengthen both systems at once . ThaddeuThe Three Delays Model is comprised of three phases. Each phase is modified by factors affecting utilization and outcomes, including socioeconomic and culture factors, accessibility, and the quality of services. Phase I centers on the decision to seek care, which can be influenced by societal norms and poor knowledge. Resources such as time and money often limit the ability of those who intend to use social services. Phase II includes identifying and traveling to facilities, and is influenced by the distance and transportation infrastructure between villages and the appropriate facilities. Phase III involves receiving adequate and appropriate care at facilities. Factors in this phase affect both utilization of services and outcomes. Provider competency, availability of commodities, and communication influence this third phase.The Three Delays Model has been widely used across development settings from Malawi to Haiti to Indonesia to explain high rates of maternal mortality –16. In IQualitative data were collected from four districts across North Sumatra (SUMUT) and West Nusa Tenggara (NTB) in June and July 2015. SUMUT, a large, mountainous, and heavily forested area, is the fourth most populous province in Indonesia, with over 13.5 million people  by themselves, and nor do we. Most of the people in the sub-villages are like that.”“Others thought the problem resulted from insufficient efforts by civil registration officials and other authorities to inform communities about the official registration process. As one male participant from SUMUT opined,They should explain the process well and make it easy. If they did that, then maybe all of us would have certificates.”“Community members also reported finding the registration process complex, confusing, and time-intensive. Many did not know how to start an application or what was required. As one CSO member from SUMUT described, “I’ve gotten married five times, but no marriage certificate at all. Not even one.”“Obtaining a marriage certificate–which until early 2016 was required in order to include the father’s name on a child’s birth certificate–was particularly challenging for many parents. This challenge was especially significant in NTB, where polygamy is common and remarrying several times is customary. Rather than paying the costs of divorce and remarriage, couples simply forego registering their marriage. One male participant from NTB explained,Without the parents’ marriage certificate, children were provided birth certificates without a father’s name, which many community members found stigmatizing. Not having a marriage certificate delayed birth registration because many unregistered couples did not want their children’s birth certificates to exclude the father’s name. One CSO member recounted the following story about a second wife in a polygamous marriage who had asked for help registering her child:She wanted to obtain a birth certificate for her child because her child wanted to go to school. When the birth certificate was issued, the child was enrolled in the school, but the teacher asked why the father’s name was not on the birth certificate. The wife came to me and asked me [why that was the case] and I said because she had no marriage certificate as required for a [complete] birth certificate, and told her to explain that to the teacher. The officer from registration office does not want to issue birth certificates with the mother and father’s name if the parents do not have a marriage certificate. [The mother] looked agitated, upset, and disappointed.” .“ome people only have a religious wedding and thus do not have a marriage certificate, and cannot apply for [their children’s] birth certificates.”“[S]Many participants also mistakenly believed that marriage certificates were mandatory for registering their children’s births. As one male participant from SUMUT explained,They tell us to bring a witness. That means we have to pay for the witness. I understand the need for a witness but I don’t like the idea of having to pay for the witness to go to court. I need that money.”“The legalization process that couples without marriage certificates had to undergo at the religious court in order to produce a birth certificate with both parents’ names required them to bring witnesses, visit the court several times, and, in many cases, spend additional money. As one female participant from SUMUT explained,So this person migrated from Lombok and wanted to apply for a family card. But this person was asked to return to Lombok to obtain a statement letter for relocation. This person does not have any money; thus, the person does not own any family card up to this day.” .“Marriage certificates were not the only problematic requirement. Many parents had expired identity cards or had not procured the appropriate documentation, such as a birth notification letter. In SUMUT, for example, a migrant family originally from Lombok was turned away when applying for their family card, which is required for a child’s birth certificate. They had not known to update their residential status with an official migration letter before travelling to the registration office. As a CSO member recounted,These additional complications factored heavily into decisions to seek birth registration services.Once parents decided to register their children’s births, they had difficulty accessing registration offices in the district capital. The delay in accessing services at government offices was primarily due to a combination of factors regarding information, infrastructure, and resources.We lived in the sub-village and [birth certificates] are made in the city. We don’t even know where the office is.”“Residents in rural areas rarely had contact with the district capital. Many did not know which offices to visit, let alone where they were located. As one male participant from NTB noted,The problem is that the distance is too great. We don’t have the money, and we are too busy to make the time.”“Participants in all study areas reported that the distance to the registration offices and the time needed for the commute delayed birth registration. One community in NTB even held demonstrations to request services closer to their village. Applicants in Langkat had to drive up to three hours each way to reach the registration offices. As one male participant from SUMUT elaborated,Some roads there are still in a poor condition, and also, [applicants] have to go back and forth by motorbike taxi. People who don’t have motorbikes take days to process [their certificates].”“Poor roads and a lack of public transportation made trips to civil registration offices an uncomfortable and costly endeavor. As one CSO member from NTB reported,I had to pay money for [the village leader’s] transportation and accommodations. The official here had to wait until he had enough applicants before he could go to [the district capital].”“In addition to belaboring birth registration, these obstacles also fed back into the first phase delay, as they discouraged people from wanting to apply in the first place.To avoid commuting to district offices, communities submitted their applications to one individual, usually the village leader, who then delivered the applications to the registration office. These individuals usually charged a transportation fee, but, in order to reduce costs, tended not to submit the applications until they had several at once. This created a further registration delay. As one male participant from SUMUT reported,Those who managed to overcome the challenges above often faced additional challenges after arriving at district registration offices. Errors in required documents were common, such as a misspelled name or an incorrect date. Because of strict policy regulations and input procedures within the civil registration management information system, civil registration providers rejected applications with spelling or date inconsistencies between documents. As one participant recalled,I once saw this at a civil registration office, far away. This person was there from morning to evening and yet her certificate wasn’t finished. She cried and begged. She only had a little mistake and they refused to help her.” .“According to participants, many of these inconsistencies resulted from simple clerical errors in the documents required for registration applications, while others were influenced by cultural practices. In Lombok, parents traditionally add their first child’s name to their own, and also change their names when they make the pilgrimage to Mecca. If parents use their new names on any of the documents required for the newborn’s birth certificate, the application can be rejected. Furthermore, if this happens and the officer does not catch the discrepancy, birth certificates may be printed with the parents’ non-legal names, potentially creating problems in the future.mark up their age—even if the kids are still underage—to get [officially] married.”“Acceptance of child marriage by local leaders was another cause of inconsistent documents. One CSO participant described an underage couple that had wedded without registering their marriage. When they wanted to produce a birth certificate for their child, they falsified their age to comply with Indonesia’s legal age of marriage. As one CSO member from NTB explained, if child applicants are already religiously married, sometimes officerEven to submit the requirements, we have to queue for the whole day, and we would still not necessarily get our turn on that day. Sometimes we have to wait until the day after, and go back and forth again.”“Many community members reported that they could not submit their applications even when they had all the requirements. Offices were often understaffed and did not have enough blank certificates available, and several reportedly closed early. One CSO member from NTB shared a typical experience:here are always people demanding immediate services every day. If possible,”“[t]the official continued, applicants want their birth certificates“processed in a day. It would be even better for them if we were able to process [their applications] within half an hour.”Participants reported that, once they submitted their applications, they waited weeks and sometimes months before picking them up. Registration officials reportedly had inadequate human resources and budget available for processing the volume of applications they received. Officials felt the practice of waiting until a birth certificate was required to begin the application made community members rush unnecessarily through the process. As one official from SUMUT said,I don’t mind waiting if there is a certainty that the birth certificate will be issued. Whether it’s three days or one week. What I don’t like is having to go to the office all the time [to check on the status of my application].”“Community members reported that there was no system to notify applicants when documents were ready. Applicants had to check their status with the officer repeatedly, often in person. As one female community member from SUMUT said,afraid their documents would not be processed if they don’t give a tip.”“Participants in SUMUT reported the same tendency. As one male community member explained,You need to pay the money first. All the other requirements such as copies of marriage certificates, family cards, and such things can follow later, so long as you pay them some money.”“Bribes, solicited and unsolicited, were reported as being used to expedite services across study sites. One male participant from NTB expressed a common sentiment that community members werePoorly communicated information, errors in printed documents, long wait times, and a lack of transparency in the application process were interpreted by many as poor quality service. This inadequate service also compounded the Phase II delay, as applicants were forced to travel to registration offices several times to complete their applications or to check their application status. The expectation of poor quality service and the costly and lengthy travel times in turn fed back into Phase I delays, in which parents decided to forestall registering their children’s births.These results demonstrate the relevance of Thaddeus and Maine’s model to civil registration in rural SUMUT and NTB. The focus group discussions confirmed findings from previous studies of civil registration in Indonesia, where cost, distance, application information, and a complex application process obstructed access to birth certificates for children in poor and rural settings . UnsurprWithout question, the cost of birth certificates discouraged many parents in low-income households from registering births during the first few years of a child’s life. Because Indonesian authorities and service providers rarely required young children to have birth certificates to benefit from government programs, parents often preferred to spend their money on more immediate concerns, such as medical care. In fact, many participants said that they delayed registering their children’s births until the certificate became valuable to them, such as during school enrollment, even if it meant paying more money.Parents’ willingness to spend more money for delaying birth registration may help to explain why previous attempts to remove application fees and impose late-registration fines did not lead to rapid increases in birth registration , 20. As This finding suggests that in order to address Phase I delays and achieve improvements in the demand for timely birth registration, authorities should focus on enhancing the value of birth certificates earlier in children’s lives rather than on deterrence policies that increase the financial burden of applying, such as late registration fees. Connecting birth certificates more closely to programs that directly benefit young children would ensure that registration becomes valuable to parents earlier in their children’s lives. At the same time, requiring that children present birth certificates to benefit from basic services risks excluding the most marginalized populations from those services, especially considering the challenges that many families face in accessing civil registration services , 24. In Applying the Three Delays Model also helps to parse the multiple effects that single factors may have on birth registration. The long distance to services for instance directly created delays in registration. If an applicant had to drive three hours to the district registration office to submit an application, rather than submitting it locally, that was three hours that the registration official was delayed in reviewing the application. The expectation of long drives also led parents to delay preparing or submitting their applications. By implication, an investment in reducing the distance between applicants and services should have a dual benefit: reducing the delay in applying for birth certificates and in processing them. The finding that parents’ distance from registration services had multifold effects on their registration delays provides support for the model of delivering civil registration to the sub-district and village levels through integrated and mobile services. It also supports policies that provide authority for registration to officials below the district level , 24.Similarly, the framework of delays helps to reveal feedback effects between barriers. In Phase I, the decision to delay birth registration until the moment a child needed the certificate led parents to rush the application process. This in turn led to complications with Phase III, including errors in application forms, dissatisfaction with processing times, and negative exchanges with registration officials. These experiences then discouraged future applications, contributing to the Phase I delays. Examining the relationship between these barriers provides a deeper understanding of how communities experienced the registration process, with important insights for civil registration strengthening programs. One implication is that efforts to build demand for birth registration, for instance by increasing community awareness about the uses of birth certificates, are likely to be hamstrung without commensurate efforts to improve the supply of capable and friendly registration staff.Applying the Three Delays Model to birth registration encourages cross-sector learning. While this article does not intend to compare obstetric care with civil registration, the several decades of experience tackling the barriers of distance, cost, and quality of care in the reproductive health field can be adapted to inform effective interventions for civil registration. Using a shared framework highlights the natural overlap between birth delivery and birth registration and promotes leveraging existing health approaches, such as voucher systems to overcome transportation barriers for the poor .Crossover already occurs between primary health and civil registration. In Ghana and Ethiopia, community health workers were trained to register births to reduce the transportation burden in remote areas –29. In BPrimary health interventions are also relevant to the Indonesian civil registration system.The country’s civil registration system parallels and often intersects with the primary healthcare system, creating opportunities for the two systems to mutually reinforce one another. As a result of efforts to reduce rural, maternal mortality dating back to 1989, midwives are often the most accessible healthcare provider for households in Indonesia , 30. In In many districts and cities across Indonesia, local governments have started to formalize the relationship between the health and civil registration sectors, whether through local regulations or formal cooperation agreements. In the city of Surakarta, staff at hospitals and birthing centers facilitate birth registration and input birth data into the population registry . In the The applicability of the Three Delays Model to connect primary healthcare and civil registration does have limitations. While the Three Delays Model in this study looks at birth certificate ownership, registration is generally an intermediary output to access other social services like education. Thus, improving the accessibility and the quality of the civil registration system does not automatically translate to increasing the utilization and positive outcomes of health or other basic services. This diverges from the healthcare context, where improving the quality of obstetric services directly affects the ultimate outcome of reducing maternal mortality. As such, reducing delays such as Phase I’s “decision to seek care or services” may be more difficult to achieve in the case of birth certificate ownership, whose negative outcome is not as severe as delaying obstetric care. The different implications of the results found by using the Three Delays Model should be accounted for when determining solutions to overcome barriers and similarly to adjust expected outcomes for reducing maternal mortality versus increasing birth certificate ownership.Limitations for this study are primarily due to our selection of study sites and participants. The CSO members who helped the research team identify study participants also assisted community members to apply for birth certificates and played a role in the delivery of these services. This selection method likely left out more vulnerable community members, who were unknown to the CSO workers, and whose participation may have identified additional barriers.The majority of the study participants had registered their children’s births. Participants were thus fairly aware of the civil registration system and how to navigate it successfully. Part of this knowledge may have been due to the site selection. All of the communities visited had received civil registration awareness campaigns and integrated mobile service events to register children. Although none of the participants had directly accessed the mobile service units, there may have been a spillover effect making them more aware of the importance of and requirements for birth certificates. Our sample may have had greater knowledge of the legal identity process and perceived importance of documents. Attempts were made to reduce this bias by also including randomly selected community members who participated in a household survey simultaneous to this research.Finally, this study cannot be generalized to the broader Indonesian civil registration system as it excluded important aspects of that system, most notably death registration. The Three Delays Model may be useful in characterizing the challenges related to death registration, especially considering the health sector’s traditional responsibility of ascertaining and certifying cause of death. Such an analysis is beyond the scope of this article.Identifying and understanding the relationship between the barriers to accessing high quality social services is crucial. The Three Delays Model, originally developed to conceptualize factors contributing to maternal mortality, helps capture this complexity in the Indonesian civil registration system. Dividing the process of applying for civil registration documents into three phases offers useful insight for policies to promote civil registration ownership. Ultimately, in order to reach its ambitious target of registering 85 percent of children’s births by 2019, Indonesia’s government will likely need to formalize the role of the primary healthcare system in working with the civil registration sector , 24. Not


The current surge of interest in multiferroic materials demands specialized measurement techniques to support multiferroics research. In this review article we detail well-established measurement techniques of the magneto-electric coupling coefficient in multiferroic materials, together with newly proposed ones. This work is intended to serve as a reference document for anyone willing to develop experimental measurement techniques of multiferroic materials. Multiferroic materials are defined as compounds that display at least two ferroic order states. The multiferroic phase could be formed by any possible permutations of these order states: magnetic-electric, magnetic-elastic, electric-elastic or magnetic-electric-elastic. Depending on how these phases are mixed and co-exist, typical multiferroic structures are either single-phase compounds or composites. Single-phase multiferroic materials are defined as homogenous compounds and chemically isotropic, in which electric, magnetic and possibly elastic/piezo-elastic order states coexist at any point or given location within the material. Single-phase multiferroics display extremely interesting physical properties, but they are rather limited in terms of their versatility because of their scarcity ,2, requiTo facilitate the advancement of our understanding of multiferroic materials and their physical properties, there is demand for detailed specialized measurement techniques designed specifically for multiferroic materials. The majority of researchers working in the field of multiferroics have most likely migrated from the solid-state magnetism or ferroelectrics/piezo-electrics research communities, so, in most cases, they have excellent skills and capabilities in only one of the two research fields.In this review article we aim to address this problem by reviewing the most useful measurement techniques of magneto-electric coupling in multiferroics and proposing some new ones. The article is intended to serve as a reference point for anyone, experienced or new to the field of multiferroics, who is interested in characterization techniques for multiferroic materials.M), polarization (P), strain (ε), microstructure characteristics, images of ferroic domains, crystallographic structure and crystal symmetries, phase transitions, process resonances and relaxation effects, to name a few. The metrologies associated with these measurements are well known and beyond the scope of this review article.For a given multiferroic material, a typical set of experimental characterisation techniques would involve structural measurements, microscopy, dielectric/piezoelectric measurements and magnetic measurements, all under various time, temperature, mechanical and external field conditions. Indeed, these measurements are very valuable as they offer detailed information about the sample and, most importantly they can help confirm the existence of a multiferroic phase by detecting at least two co-existing ferroic order states, as defined earlier. Typically such measurements would yield magnetization  of the sample due to the application of an electric field (E):P) due to the application of a magnetic field (H):Thermodynamically it is predicted that the magneto-electric effect occurs in materials where magnetic-electric or magnetic-electric-elastic phases coexist . The magα . The magEα = Depending on the choice of independent thermodynamic variables, relation (1) can be also written as the partial derivative of magnetization in respect with the applied electrics field, ijα, with nine components:In any case, the true representation of magneto-electric coupling coefficient is actually in the form of a magneto-electric susceptibility second rank tensor, According to the Maxwell equations, the electrically and magnetically induced ME coefficients are thermodynamically equivalent :(4)αijEα11, α22, α33 or non-diagonal α31 and α13 is non-zero.Although the magneto-electric tensor has nine components, in most of the studies only one of these components is non-zero. This depends on the sample/crystal symmetries, sample geometry and geometry of the applied external fields. Usually for a given experimental geometry only one of the diagonal components Let us now examine the electrically and magnetically induced ME coefficients:Using Equation (1) in Equation (6) we obtain:rε, rµ are the dielectric relative permittivity and relative magnetic permeability of the multiferroic, respectively. One method of deriving Equation (9) makes use of the relation linking speed of light to ε0, µ0  can be interpreted as the inverse velocity of propagation of electromagnetic radiation in a multiferroic medium, v ≤ c, so that c on both sides, we get Equation (8) shows that all components of the magneto-electric coupling coefficient tensor must be positive since materials with negative permittivity and permeability do not exist, while the permittivity and permeability of the vacuum are positive values. Although not showing the full derivation, in most publications Equation (8) is written in non-tensor form as:V is the voltage and t is the thickness of the dielectric structure, since E = V/t, the following relation for the magnetically induced magneto-electric effect is obtained:VHα is the magnetically induced voltage magneto-electric coefficient defined as:A closer inspection indicates the possibility to further manipulate Equation (5). If Hα = ε0⋅rε⋅VHα [Hα and Eα are both expressed in [s/m] units. However, the more practical voltage magneto-electric coefficient, VHα (see Equation (12)) is expressed as [V/A] in SI units and [V/cm⋅Oe] in CGS units, which are also utilized in most practical applications and scientific measurements [The voltage magneto-electric coefficient is the main parameter used in analysing experimental measurements and designing various applications based on multiferroics. The relationship between the magnetically induced magneto-electric coupling coefficient and the voltage magneto-electric coefficient is: 0⋅εr⋅αVH . We haveurements ,23. In wt is the thickness of the ferroelectric layer in the case of laminates, or the thickness of the sample in the case of a single-phase composite, H is the amplitude of the externally applied magnetic field and V is the measured voltage. According to Equation (13), the voltage response of a multiferroic varies linearly with the amplitude of the applied magnetic field. It is important to mention that this relation is valid to both single-phase and composite multiferroics. However, the H field in this case is in fact an AC magnetic field and, unless one has the ability to apply large amplitude AC magnetic fields, the measurement requires the application of a DC magnetic field bias. The magnetic DC bias field couples with the AC magnetic field to produce a pseudo-piezo-magnetic linear response, which in turn modulates the electrical voltage response. The voltage magnetically induced magneto-electric coupling coefficient is determined experimentally in the following way:(a)Bias the multiferroic sample under an optimal DC magnetic field bias;(b)Apply an AC magnetic field of fixed frequency and amplitude at 0 or π angle, or any non-transverse direction, to the DC magnetic bias field ;(c)Measure the voltage response output of the multiferroic at various amplitudes of the applied AC magnetic field, at fixed DC magnetic bias and fixed frequency of the AC field;(d)Plot the measured voltages as a function of the amplitude of the applied AC magnetic fields;(e)From the obtained linear graph, as predicted by Equation (13), the magneto-electric coupling coefficient is determined as the slope of the graph divided by the thickness of the dielectric.Magnetically induced magneto-electric coupling coefficient is described by Equation (2), or alternatively by the magnetically induced voltage magneto-electric coefficient, Equation (12). Since it is much easier to measure a voltage than electric polarization, Equation (12) and the measurement of the voltage magneto-electric coefficient are preferred. Integrating Equation (12) we obtain a relationship between the voltage induced on the electrodes of a multiferroic device and the amplitude of an externally applied magnetic field:A diagram of a typical measurement system is shown in This measurement technique is by far the most utilized in literature ,38,39,40VHα is a complex function of material parameters, compliances, DC magnetic bias field and frequency. This complex function has only been derived analytically for some special cases of composite multiferroics [The answer is related to the fact that the voltage magneto-electric coefficient, ferroics ,42,43. EIn terms of measurement of the magnetically induced magneto-electric coupling coefficient, another possible approach is to measure directly the electric polarization induced in the sample by the application of a magnetic field, Equation (2). Unlike the above technique, which involves the measurement of the open circuit induced voltage, this method involves the measurement of the short circuit-induced current, i.e., electric polarization. In this case the experimental set-up is similar to that used to measure electric polarization hysteresis loops, except that instead of applied voltages, the multiferroic sample is excited by external AC and DC magnetic fields. The easiest way to perform this experiment is to modify a commercial polarization-electric field hysteresis measurement instrument to allow the application of AC and DC magnetic fields.Equation (1) describes the electrically induced magneto-electric coupling, although most of the time the coefficient is expressed as (a)Place the multiferroic sample in a suitable magnetometer;(b)Under zero applied magnetic field, excite the sample with an AC electric field/voltage of fixed frequency;(c)Measure the magnetization of the multiferroic sample at various amplitudes of the applied AC electric field/voltage;(d)M values as a function of the amplitude of the applied AC electric field/voltage;Plot the measured (e)M = M(E), or the slope of the graph times the thickness of the dielectric if M = M(V) is measured;From the obtained linear graph, as predicted by Equation (14), the magneto-electric coupling coefficient is determined as the slope of the graph if According to Equation (14), the electrically induced magneto-electric coupling coefficient is determined experimentally in the following way:αE coefficient, and the effect is expected to be largest when the frequency of the AC electric field/voltage matches the electro-mechanical resonance frequency of the sample.Just as in the case of the magnetically induced coupling, there is a frequency dependence of the The experiment can be easily performed in any magnetometer with small modifications of the sample holder in order to allow the application of a voltage to the sample’s electrodes. These instruments could be Vibrating Sample Magnetometer (VSM), Alternating Gradient Force Magnetometer (AGFM), and Superconducting Quantum Interference Device (SQUID) magnetometer, to name a few. The main disadvantage of these instruments is the complexity of addressing electrically the sample, as they are dynamically operated with the sample under physical movement, or they are utilizing delicate sample holders and detection that are affected by the addition of electrical wires, electrodes, etc.Although with suitable modifications any magnetometer could be used to perform electrically induced magneto-electric coupling measurements, by far the most convenient way to measure this coupling is using a Magneto Optic Kerr (MOKE) magnetometer. In this technique the sample is static and the magnetization changes are detected optically, so addition of electrical wires and voltage excitations can be easily deployed. Reflection of a beam of linearly polarised light from a magnetised surface causes an orthogonal polarized component with the principal axis rotated with respect to the incoming light. The amount of rotation and ellipticity induced in the reflected beam is proportional to the magnetisation of the sample and this phenomenon is known as the magneto-optic Kerr effect (MOKE) ,45,46. AAlthough there are numerous studies reporting experimental demonstration of electrically induced magnetization change ,48, switPiezo-electric measurements involve the experimental determination of the piezo-electric coefficients or compliances of a material. These techniques are well developed and have been introduced mostly to characterize the piezo- and electro-mechanical properties of ferroelectrics utilized as mechanical actuators. Since such measurements are readily available to perform on commercial instruments, would it be possible to extract the magneto-electric coupling of a multiferroic from piezo-electric measurements? This question has been already answered  and the P is the electric polarization, E is the applied electric field, ε is the dielectric permittivity, σ is the mechanical external applied stress, ed is the piezo-electric coefficient, effα is the effective magneto-electric coupling coefficient, H is the applied magnetic field and the above equation has been written using condensed matrix notation with m = 1, 2, 3, 4, 5, 6 and i, j = 1, 2, 3. Imposing short-circuit measurement conditions, so that E = 0, then P = D, where D is the electric displacement, so Equation (15) becomes:Assuming that a multiferroic material at constant temperature contains both electric and magnetic phases, exhibiting piezo effects, piezo coupling effects and magneto-electric coupling, then using the external applied fields and stress as independent variables and following a thermodynamic formalism, it has been shown that the electric polarization of the multiferroic sample due to the application of an external stress, electric field and magnetic field is :(15)Pi=σ) and magnetic field (H). Let us remember that we assumed a hypothetical instrument capable of measuring de and we want to determine effα. To achieve this, we rearrange Equation (16):Equation (16) gives the electric displacement of a multiferroic sample at constant temperature due to the application of an external stress (ijeffα in units of (C/m2⋅Oe) and the differential is the slope of the linear function (Equation (17)):According to Equation (17), the piezo-electric coefficient of a multiferroic sample varies linearly with the applied external magnetic field. From Equation (17) we can obtain by differentiation the short circuit This experiment has been successfully performed using a quasi-static piezoelectric coefficient measurement (known as the Berlincourt instrument), which has been modified to accommodate the application of DC and AC magnetic fields see .α31eff is determined here [The modified instrument can measure the piezoelectric coefficient and the magnetically induced ME coupling coefficient of multiferrroics. Both magnetic fields are applied in the 1 direction  and they are parallel to each other, while the mechanical stress is applied to a multiferroic sample in the 3 direction. According to this measurement geometry, the ned here . The DC effα expressed in units of V/m⋅Oe. The open circuit effα coefficient can be determined from piezo-electric measurements by using the relationship between the short circuit piezo-electric coefficient ed and the open circuit piezo-electric coefficient eg [ε is the dielectric permittivity of the material, ε0 is the permittivity of the vacuum (ε0 ≅ 8.85 × 10−12 C/m⋅V) and rε is the relative dielectric constant of the material. Using Equations (18) and (19) we obtain the general expression of the open circuit magneto-electric coupling coefficient (units of V/m⋅Oe) as:There are, however, other measurement techniques in which the piezo-electric coefficient is determined in open circuit conditions rather than short circuit, such as laser interferometry. Indeed, most of the magneto-electric coupling measurements are performed in open circuit conditions, with magneto-electric coupling coefficient, cient ge :(19)dij(a)Place the multiferroic sample in a suitable piezo-electric testing instrument;(b)The instrument must be modified to allow the simultaneous application of AC and DC magnetic fields to the sample;(c)Measure the piezo-electric coefficient at various amplitudes of the applied AC magnetic field at fixed DC optimum bias field;(d)Plot the piezo-electric coefficient values as a function of the amplitude of the AC magnetic field;(e)From the slope of the linear graph, determine the magneto-electric coupling coefficient using either Equation (18) or (20), depending whether the experimental conditions are short-circuit or open-circuit.Equations (18) and (20) allow the elegant extraction of the magneto-electric coupling coefficient from piezo-electric measurements performed in either short circuit or open circuit conditions. This approach is very useful for multiferroic metrologies because of the rich variety of existent techniques for the measurement of the piezoelectric coefficient. According to this method, the magnetically induced magneto-electric coupling coefficient is determined experimentally in the following way:Scanning Probe Microscopy (SPM) is a generic term that defines a collection of scanning microscopy techniques all based on an atomic force microscope. There is a huge variety of possible microscopy scanning modes, but for multiferroic testing Magnetic Force Microscopy (MFM) , Piezo FaF is the total atomic repulsive force on the surface and occurs only in contact mode; magF is the interaction force between the sample magnetization and the tip’s magnetic moment, defined for the case of a magnetic tip as:eF is the electrostatic force interaction between the charge on the tip and the surface charge distribution. This force occurs in both contact and non-contact mode if a voltage is applied to the tip:tipV = voltage applied on the tip, surfaceV is the surface potential, C is the tip–surface capacitance and depends on the tip geometry.piezoF is the piezo-mechanical force that occurs only in contact mode for samples that display piezo-electricity. If x is the piezo-electric strain, Δz the sample displacement and z is the sample thickness, then:HF is the interaction force between the magnetic tip and the applied external magnetic field, defined as:Having defined all the dominant forces that occur in SPM measurements and having their occurrence detailed in d33 measurement is performed. Essentially this is the technique described in It is also important to stress that a true magneto-electric coupling measurement using SPM is in fact a static measurement where the tip is not scanning the surface but remains static. The data are acquired at a local point and the results are not images, although topography, MFM or PFM images could be acquired prior to the coupling measurement. The main benefit of the SPM technique is the ability to measure magneto-electric coupling at much reduced scales, including nanostructures. A typical measurement system could be a standard SPM modified to allow the application of AC/DC magnetic fields to the samples being tested , while aBmod,λ ~ B2. The total field experienced by the sample is then:Magnetically induced magneto-electric coupling discussed in pT/Hz ,37. At fpT/Hz . In thisB field contains a product term, which expresses the frequency conversion effect:ωmod and acω are the angular frequencies of the alternating bias and the small AC signal, respectively. The fundamental effect of the application of an alternating magnetic bias field is to dynamically change the slope of the magnetostriction curve, which is seen by the small AC magnetic excitation field inducing the magneto-electric effect. In turn, the slope describes the signal transfer characteristics of the superposition of Bmod and acB into a magnetostrictive elongation at the instantaneous operating point corresponding to the modulation frequency.Assuming sinusoidal signals as described in Equations (26) and (27), the square of the total ωres is known, then performing the experiment so that either If the electro-mechanical resonance frequency of the multiferroic structure, Besides offering versatility to drive the device resonantly at non-resonance excitation frequencies, this technique is also suited to wideband signals as well as non-sinusoidal signals, so various frequencies can be converted sequentially. Another significant advantage of the frequency conversion technique is the decreased sensitivity to vibration distortions at low frequencies and a reduced sensitivity against undesired acoustic crosstalk . Using tapproach . The freT is the temperature, C is specific heat capacity of the system per unit volume C = T (S/T), µ0, ε0 are the magnetic permeability and dielectric permittivity of vacuum, mχ and eχ are the magnetic and electric susceptibilities, Eα and Hα are the electrically and magnetically induced magneto-electric coupling coefficients, M is magnetization and P is the electric polarization of the multiferroic system. A full derivation of the multicaloric effect is given in [E,HT < 0) is achieved for an adiabatic depolarisation/demagnetisation, making this effect very attractive for solid state refrigeration. However, besides solid-state refrigeration applications, the multicaloric caloric effect could also be used to develop metrologies for magneto-electric coupling coefficient estimation from thermal measurements. In order to maximize the multicaloric solid state cooling effect, a multiferroic material must have identical (or similar) ferroic phase transition temperatures to the constituent phases and the device must be operated at exactly (or close) to this transition temperature, where the partial derivatives cmT ≈ ceT ≈ T. Contrary to this requirement, a magneto-electric coupling measurement based on the multicaloric effect requires multiferroics with very different transition temperatures of their ferroic constituent phases. In this way, the different contributions to ΔE,HT in Equations (30) and (31) can be easily separated by performing the experiment at a suitable base temperature T. Let us make the following substitutions in Equations (30) and (31), M/T = mγ and P/T = eγ. Let us also assume that the transition temperature of the magnetic phase is much larger than the transition temperature of the electric phase, cmT > ceT. If the measurement is performed at an operating temperature T close to one of the transition temperatures, then depending whether T = cmT or T = ceT, either M/T = mγ or P/T = eγ at the operating temperature is negligible as the slope is almost zero. Since cmT > ceT then choosing the operating temperature T = ceT results in M/T = mγ = 0 and Equations (30), (31) in integral form become:In 2012 a new caloric effect has been proposed, in which multiferroic materials are utilized to produce a temperature change in response to adiabatic changes of variables such as volume, strain, magnetization or electric polarization. The effect was called the multicaloric effect. Solid-state caloric effects have been known since 1917 when Weiss and Piccard made the first observation of a caloric effect in magnetic materials  and the given in . AccordiDividing Equation (33) by Equation (32), we obtain the magnetically induced magneto-electric coupling coefficient:cmT < ceT, then choosing the operating temperature T = cmT results in P/T = e =γ 0 and applying the above formalism, the electrically induced magneto-electric coupling coefficient can be estimated as:In a similar way, for multiferroic materials in which M/T = mγ or P/T = eγ as they are reduced from the equations. One only needs to know the values of the magnetic and dielectric susceptibilities of the material under test, the values of the applied external fields, which are controlled by the experimenter and the values of the temperature change, which are measured experimentally. A possible instrument capable of measuring magneto-electric coupling coefficient from thermal measurements is shown in (a)Place the multiferroic sample in vacuum chamber in adiabatic conditions;(b)The instrument must be capable to apply magnetic field and electric fields to the sample, as well as to measure accurately the temperature change of the sample;(c)A temperature reservoir can be set at a desired operating temperature and then brought in contact with the multiferroic sample via a thermal switch;(d)Apply a large E field to the sample;(e)E field is ON, if cmT > ceT, choose the operating temperature T = ceT and bring the sample at T = ceT via the thermal switch;While the (f)Cut the thermal link to the reservoir;(g)E applied field to zero;Reduce the (h)ET;Measure the temperature change Δ(i)T = ceT;Bring the sample back to the operating temperature (j)Apply a large magnetic field and then bring the sample to adiabatic conditions;(k)HT;Reduce the applied magnetic field to zero and measure the temperature change Δ(l)Use Equation (34) to derive the magnetically induced magneto-electric coupling coefficient.(m)cmT < ceT, choose the operating temperature T = cmT and repeat the above procedure;If (n)Extract the electrically induced magneto-electric coupling coefficient using Equation (35).Remarkably, this proposed measurement procedure does not require exact knowledge of the partial derivatives Linear magneto-electric effect induced magnetically involves the application of a suitable DC magnetic bias field and a small amplitude AC magnetic excitation field, as discussed in detail in Scientists at MIREA, Russia ,85 have 0 is the DC applied magnetic field and h(t) is the total AC applied magnetic field, h(t) = h1(t) + h2(t), where h1(t) and h2(t) are simultaneously applied AC magnetic fields:f1 and f2 are the frequencies of the h1(t) and h2(t) AC magnetic fields, respectively, then the total field experienced by the sample is H = H0 + h(t), with h1, h2 << H0. The authors showed that the voltage generated by the multiferroic due to the application of combined magnetic fields is:A is a geometrical sample factor, ed is the piezo-electric coefficient and λ(H) is the magnetostriction. Considering the non-linearity of the magnetostriction, which can be expanded into a Taylor series around H0, and using Equations (36) and (37), after some algebraic manipulation, the voltage induced due to the application of H = H0 + h1(t) + h2(t) is given by [Assuming that Hgiven by :(38)u(tu(0); the AC components u1(1) and u2(1) at the frequencies f1 and f2, respectively, due to the linear magneto-electric effect; the frequency doubling voltage components u1(2) and u2(2) at 2f1 and 2f2 frequencies, respectively; the frequency mixing voltage component mixu with frequencies f1 + f2 and f1 − f2, describing the non-linear mixing of magnetic fields. In this method the frequency mixing is due to AC magnetic fields of different frequencies being simultaneously applied to the multiferroic structure in addition to a DC magnetic bias field, while the Kiel frequency mixing method involves an AC magnetic field being applied simultaneously with an AC magnetic bias field, with frequencies carefully selected so that the mixed frequencies match the electro-mechanical resonance frequency of the device: resf = f1 + f2 or resf = f1 − f2. If et is the thickness of the dielectric component, the following magneto-electric coupling coefficients can be extracted from Equation (38):(1)The standard linear magneto-electric coupling coefficients (units of V/cm⋅Oe):(2)2):The non-linear magneto-electric coupling due to the frequency doubling voltage component (units of V/cm⋅Oe(3)2): The non-linear magneto-electric coupling due to the frequency mixing voltage component (units of V/cm⋅OeThe full derivation of Equation (38) can be found in  and showThe block-diagram of the experimental setup is shown in Multiferroics are a very important class of materials exhibiting interesting multi-functional phenomena. The combination of magnetic, polar and piezo-elastic properties makes multiferroic materials very attractive for fundamental research but also technological applications. The present challenges are the discovery and manufacturing of multiferroic materials and structures that show large magneto-electric coupling at room temperature, and the development of accurate experimental characterization techniques. In order to build a clear picture of the current available metrologies for multiferroic characterization, in this review we selected some of the most relevant techniques of magneto-electric coupling measurement in multiferroics, as well as proposing new possible ones such as the extraction of the magneto-electric coupling from thermal measurements and from SPM measurements. Using this review article, a suitable measurement technique can be selected or developed depending on the structure under test, size and thermal characteristics as well as the experimental tools available to the investigator.