Objective To describe caffeine consumption during pregnancy and its association with low birth weight (LBW) and preterm birth in the birth cohort of Ribeirão Preto, state of São Paulo, Brazil, in 2010.Methods Cohort study, with descriptive and analytical approach. Data included 7,607 women and their newborns in Ribeirão Preto, state of São Paulo, Brazil. The women answered standardized questionnaires about reproductive health, prenatal care, life habits, sociodemographic conditions, and information about coffee intake. The independent variable was high caffeine consumption (≥300 mg/day) from coffee during pregnancy, and the dependent variables were LBW  and preterm birth . Four adjusted polytomous logistic regression models, relative risk (RR) and 95% confidence interval (CI) were fitted: biological and sociodemographic conditions; obstetric history; current gestational conditions; and all variables included in the previous models.Results A total of 4,908 (64.5%) mothers consumed caffeine, 143 (2.9%) of whom reported high consumption. High caffeine intake was significantly associated with reduced education and with the occupation of the head of the family, nonwhite skin color, not having a partner, higher parity, previous abortion and preterm birth, urinary tract infection, threatened abortion, alcohol consumption and smoking. No association was found between high caffeine consumption and LBW or preterm birth in both unadjusted  and adjusted analyses .Conclusion In this cohort, high caffeine intake was lower than in other studies and no association with LBW or preterm birth was found. Maternal exposures, such as excessive caffeine consumption during pregnancy, are likely associated to low birth weight (LBW) and preterm birth. This issue has been the subject of several epidemiological studies.Caffeine , an alkaloid contained in coffee, tea, cocoa, soft drinks with cola, some medications, and stimulants, is a substance generally socially accepted in the whole world that acts as a psychoactive stimulant.Studies showed that the amount of caffeine intake during pregnancy is relatively high. The prevalence in women who had preterm birth was 68.1%,Several studies showed an increased risk of adverse perinatal outcomes when caffeine consumption was ≥300 mg/day,In Ribeirão Preto, state of São Paulo, Brazil, a birth cohort started in January 2010, which included 7,702 mothers and newborns (NB) in facilities right after childbirth. Cohort studies are considered paramount in understanding the effects of intrauterine life and of childhood conditions on adult health.Thus, the objectives of the present study were to describe caffeine intake during pregnancy and estimate the risks between high caffeine consumption with LBW and preterm birth, on the 2010 birth cohort of Ribeirão Preto, state of São Paulo, Brazil.st and December 31th, 2010; 95 twin pregnancies were excluded, remaining 7,607 mothers and NBs evaluated.This cohort is part of the Brazilian Ribeirão Preto and São Luís Birth Cohort Studies , with the main objectives of evaluating new preterm birth risk factors , perinatal health indicators, and impact on later preterm birth growth. The cohort included 7,702 mothers and their NBs between January 1Childbirth took place in eight maternity hospitals of Ribeirão Preto and, during the study period, trained personnel visited these facilities to interview the mothers and collect information about the NBs from medical records.+0 weeks), and the independent variable was caffeine intake (only from coffee). Information about daily and weekly frequency of caffeine consumption during each trimester of gestation (days/week), and type of container used were collected. No information about tea, chocolates, sodas and other sources of caffeine were recorded. Caffeine consumption from coffee during pregnancy was categorized as none, low (< 300 mg/day) and high (≥300 mg/day), according to the Care Study Group.The dependent variables were low birth weight (LBW)  and preterm birth  and NB variables . Newborn anthropometry included BW and length.Maternal age was categorized as ≤ 19, between 20 and 34, and ≥ 35 years old. Maternal education was categorized as ≤ 8, between 9 and 11, and ≥ 12 years of study. Skin color was self-referenced as either white or not white. Marital status was categorized as with or without partner. The occupation of the head of the family(STROBE) initiative.For improving the presentation of the results, we followed the strengthening the reporting of observational studies in epidemiology p < 0.05. The present study was approved by the Research Ethic Committee of the Ribeirão Preto Medical School of the Universidade de São Paulo (process n° 10400/2012), and all participants received and signed the informed consent form.Data analysis included mean (standard deviation [SD]), median (interquartile range [IQR]) or proportions . A univariate risk analysis between LBW and preterm birth, high caffeine consumption and covariates were performed. Then, four adjusted polytomous logistic regression models  were fit. The first one was adjusted for biological and sociodemographic conditions ; the second included obstetric history ; the third was adjusted for current gestational conditions ; and the last was adjusted for all variables included in the previous models. The reference value was the absence of caffeine consumption. The goodness of fit was tested using the Hosmer-Lemeshow test. All analyses were performed with Stata software, version 13.0  and SAS software, version 9.2 . Statistically significant difference was set at A total of 7,607 mothers and their NBs were included. Of these, 4,908  consumed caffeine from coffee during pregnancy, 143 of whom  ingested ≥300 mg/day. The mean BW was 3,143 g (SD = 553); 8.7% were LBW, and 1.7% were very low birth weight . The mean GA was 285 (SD = 104) days, and 14.5% of the childbirths were preterm (< 259 days).The majority of the total population studied ingested up to 500 mg of caffeine per day, with a median caffeine intake of 91.5 mg/day (IQR = 143.8); there was no difference per trimester of caffeine intake (data not shown).High caffeine intake was significantly associated with reduced maternal education, occupation of the head of the family, nonwhite skin color, and not having a partner .High caffeine intake was significantly associated with higher parity, previous abortion and preterm birth, urinary tract infection, threatened abortion, alcohol consumption, and smoking .Low birth weight was the only condition significantly associated with high caffeine consumption .Crude risks for LBW and preterm birth were 1.45 (95% CI: 0.91–2.32) and 1.16 (95% CI: 0.77–1.75), respectively. For LBW, the RR increased slightly after the adjustment, but no differences were observed . For preIn the present study, 64.5% of the pregnant women drank coffee and there was no difference per trimester of caffeine intake. Only 2.9% of these women reported high caffeine intake, without association with LBW or preterm birth.Similarly to the present study, large studies that incorporated trimester-specific questionnaires showed no difference between the trimesters.In other studies, the incidence of high caffeine consumption was higher than in Ribeirão Preto 18.9%,, possiblCaffeine consumption from coffee, tea, soft drinks with cola, chocolate, and some medications is frequently described,In the present cohort, high caffeine consumption during pregnancy was not associated with LBW or preterm birth, in crude and adjusted models. To study the associations between the independent variables and LBW and preterm birth, odds ratios (ORs) were estimated by using a hierarchized (polytomous) logistic regression model.Other studies reinforced this finding;However, some authors found an association with different caffeine levels , of the inadequate measures of caffeine intake, of the insufficient statistical power and control of confounding variables. In some studies, higher consumption of caffeine intake was found with a similar cutoff (> 300 mg/day), but including tea, chocolate and other sources of caffeine.Some studies suggest a possible effect of chemicals present in coffee and tea other than caffeine, such as polyphenols, which contribute to adverse pregnancy outcomes including preterm delivery and preeclampsia.Several limitations of the present study should be mentioned. First, the sample size was originally not computed for caffeine consumption and, therefore, a type I error cannot be ruled out. Second, caffeine intake during pregnancy was measured on a self-reported basis only after birth, a fact known to underestimate the frequency and amount of caffeine ingested by pregnant women; consequently, our study is subjected to recall bias. The information about caffeine intake were obtained by questionnaires; therefore, it was not possible to quantify neither the concentration, the brand of coffee, nor the method of preparation . The questionnaires employed did not have information about other sources of caffeine, such as tea, soft drinks with cola, chocolate, or some medications, which can influence the lower prevalence of consumption of caffeine compared with the aforementioned studies. Third, the present study was performed in a cohort of relatively healthy pregnant women with singleton pregnancies. Therefore, the findings can only be generalized to an obstetric population with a similar risk of complications. Finally, we cannot exclude the possibility of residual confounding variables.The strength of the present study was the assessment of a birth cohort followed-up since the prenatal period with a high response rate (96%). Since the data were collected at two different periods, we were able to confirm the information and to adjust the outcomes for a wide range of known confounders, such as maternal behaviors and sociodemographic factors, and possible risk factors of adverse perinatal outcomes could be registered.Therefore, more detailed studies analyzing sources of caffeine are necessary, and also to verify if any specific trimester of gestation can be more vulnerable to caffeine exposure.High caffeine intake during pregnancy was not associated with an increased risk of LBW and preterm risk in the birth cohort of Ribeirão Preto.


Women with gestational diabetes mellitus (GDM) are at greater risk of abnormal birth weight. Since the level of biochemical indicators could often affect the intrauterine growth and development of the fetus, it is of great practical significance to understand the changes of biochemical levels across pregnancy in women with GDM and to find out the indicators that play an important role in predicting birth weight.st and March 31st in 2018 were included. The data of ferritin, serum lipid profile and fasting plasma glucose (FPG) of mothers in the three trimesters of pregnancy, as well as birth weight of newborns were all collected from medical records. Multiple linear regression and multivariate logistic regression analyses were used to explore the association of the biochemical indexes and birth weight. A P value < 0.05 was considered statistically significant.The data source of this study was from the Xi'an Longitudinal Mother–Child Cohort study (XAMC), in which women with GDM with normal and high pre-pregnancy body mass index (BMI) and their newborns between January 1n = 530, 67.8%) and overweight/obesity group (OG)  according to maternal pre-pregnancy BMI. The level of ferritin in both NG and OG decreased during pregnancy , whereas the levels of total cholesterol (TC), high density cholesterol (HDL-C), low density cholesterol (LDL-C) and triglycerides (TG) all showed an upward trend . The levels of FPG in the two groups remained in a relatively stable during the whole pregnancy even though it was higher in OG during the 2nd and 3rd trimesters, whilst HbAlc levels in NG women increased (P for trend = 0.043) during pregnancy. Meanwhile, the risk of macrosomia and large-for-gestational-age (LGA) increased with the increase of FPG level (P for trend < 0.05). Multivariate logistic regression analyses results showed that only FPG level in the 3rd trimester was correlated with birth weight, with birth weight increased by 44.9 g for each SD increase in FPG level.A total of 782 mother-infant pairs were finally included and divided into normal weight group (NG) (rd trimester is an independent predictor of newborn birth weight, and a higher level of that is associated with an increased risk of macrosomia and LGA.Maternal FPG in the 3 Gestational diabetes mellitus (GDM) is defined as "diabetes diagnosed in the second or third trimester of pregnancy that is not clearly overt diabetes prior to gestation" , is one The level of maternal biochemical indicators could often reflect the health of the mother during pregnancy and their offspring. It is well known that birth weight is associated with maternal metabolic disturbances, such as hyperglycemia, dyslipidemia, and other health problems like high iron content which is suggested as the level of ferritin. Hence, it is helpful to predict and monitor the birth weight through the detection of those clinical biochemical indicator, such as ferritin, serum lipid profile, plasma glucose and glycosylated hemoglobin (HbAlc), and some of them were well documented in normal pregnant women –9. Sincest and March 31st in 2018 were included. From the medical records, we excluded subjects with type 1 or 2 diabetes mellitus before pregnancy as well as those who were not diagnosed with GDM. Patients with multiple birth, incomplete or incorrect data, and stillbirth, or women with a history of severe systemic disease such as cancer, chronic renal failure, severe anemia, or immune disorders and other endocrinopathies were also excluded. Only women with GDM with normal and high pre-pregnancy BMI who had more than one of biochemical index records were selected.The data source of this study was from the Xi'an longitudinal mother–child cohort (XAMC), which is an ongoing large-scale longitudinal mother–child cohort study to investigate the role of external and internal factors on the short-term and long-term outcomes of mothers and children . All preThe data of maternal age, parity, gestational age, admission/discharge diagnosis, sociodemographic information, anthropometric characteristics of mothers and newborns, maternal biochemical parameters including ferritin, lipid profile, such as total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), as well as fasting plasma glucose (FPG) and HbAlc were all extracted from the electronic information system of hospital. Generally, the biochemical parameters were measured in the first , middle  and third (> 28 weeks) trimesters of pregnancy.The protocol was approved by the ethical committee of Xi'an Jiaotong University (XJTU 2016–053) and the Northwest Women's and Children's Hospital (NWCH 2012–013). All patients provided written informed consent. The principles of the Helsinki Declaration were followed throughout the study.All women underwent a 75-g oral glucose tolerance test (OGTT) during 24–28 gestational weeks. The diagnosis was carried out by obstetricians based on the recommendations of the International Association of Diabetes and Pregnancy Study Groups Consensus Panel : fasting2) was calculated by maternal height and pre-pregnancy weight. Mothers were divided into two groups according to pre-pregnancy BMI: Normal weight group  and Overweight/Obese group  . Contrarily, lipid profile data showed pronounced elevations of TC, HDL-C, LDL-C and TG during the whole pregnancy . Moreover, in the 2nd and 3rd trimester, the HDL-C level of NG was higher than that of OG , while the TG level of OG was significantly higher than that of NG during the whole pregnancy . However, the levels of FPG and HbAlc in two groups were relatively comparable during the pregnancy. Even so, comparisons between the groups showed that the FPG level of OG was higher than that of NG in the 2nd  and 3rd trimester , while HbAlc level was only higher than that of NG in the 2nd trimester .We analyzed the changing trend of the average level of biochemical indexes in different trimesters in NG and OG, respectively Fig. . The resst trimester and FPG level in the 3rd trimester were positively correlated with birth weight. For each SD increase in TG and FPG level in the 1st trimester and FPG level in the 3rd trimester, birth weight increased by 89.0 g, 61.9 g and 58.9 g, respectively. However, there was a negative correlation between maternal ferritin level and birth weight in the 3rd trimester, and birth weight decreased by 51.1 g for each SD increase in ferritin level. Then, the indexes with P < 0.2 in Table 3). After adjusting for maternal age, educational level, pre-pregnancy BMI, gestational age, gestational weight gain, parity and newborn sex, only the FPG level in the 3rd trimester was positively correlated with birth weight, with birth weight increased by 44.9 g (14.0–75.7 g) for each SD increase in FPG level.A simple linear regression analysis between each Z-score standardized index and birth weight was made Table . We founrd trimester into tertiles and calculated the proportions of macrosomia and LGA in each category , with 12.1% and 23.8% of marcrosomia and LGA, respectively in the 3rd tertile. Logistic regression analyses results (Table rd trimester (P for trend < 0.05). Even in Model 3 after adjusting for all confounders mentioned above, the risk of macrosomia and LGA increased by 1.44 and 1.50 times in the 3rd tertile of FPG level compared to the 1st tertile.Next, we divided the FPG level in the 3ory Fig. . As expets Table  showed tIn this study, we explored the trend changes of ferritin, serum lipid profile, plasma glucose and HbAlc levels in different pregnant trimesters in women with GDM with normal and high pre-pregnancy BMI and analyzed their effect on newborns’ birth weight. We found that regardless of pre-pregnancy BMI, the level of ferritin showed a downward trend during pregnancy whereas the levels of lipid profiles all showed upward trends while the levels of FPG remained relatively stable, although the average levels were generally higher in women who were overweight/obese before pregnancy. However, only FPG in the third trimester was positively associated with birth weight and the risk of macrosomia and LGA.A large number of studies have shown that ferritin is closely related to the risk of GDM , 18–22. Serum lipids are important indicators to reflect the health of the mother and fetus during pregnancy and dyslipidemia during pregnancy could increase the risk of adverse pregnancy outcomes such as GDM, preeclampsia and preterm delivery , 29. Thest trimester until the 2nd trimester, and increased towards the 3rd trimester in women with pre-gestational diabetes [nd and 3rd trimester, while HbAlc level was higher than that of NG in the 2nd trimester. This is consistent with the finding that the values of OGTT in obese women were on the high side in the second trimester [rd trimester than women with normal weight [rd trimester and birth weight (Table rd trimester could increase the risk of macrosomia and LGA. The risk of macrosomia and LGA in GDM patients with FPG > 4.71 mmol/L in late pregnancy is more than twice as high as that in women with FPG ≤ 4.70 mmol/L based on the data of our study (Table rd trimester. However, a large cohort study of healthy pregnant women found that FPG in both 1st and 3rd trimester of pregnancy were associated with birth weight, and there was a negative correlation between HDL-C and birth weight in the 3rd trimester [Glucose metabolism is of particular concern throughout pregnancy and often played crucial role in the development of GDM. Previous studies showed that the mean HbA1c level decreased from the 1diabetes , and thediabetes . In thisrimester . In addil weight . The resrimester , which iOne of the major strengths of our study was that, to the best of our knowledge, this was the first time the associations of key clinical maternal biochemical indexes of three trimesters with neonatal birth weight were examined. Previous studies indicated that the level of maternal biochemical indexes, such as ferritin, serum lipid, plasma glucose and so on may have a predictive effect on neonatal birth weight –13. Howerd trimester was an independent predictor of newborn birth weight, and that is associated with an increased risk of macrosomia and LGA. These observations highlight the importance of controlling the levels of FPG levels of women with GDM during pregnancy clinically.In women with GDM regardless of pre-pregnancy BMI, the level of ferritin decreased whist the levels of lipid profiles increased, and the levels of FPG remained relatively stable during the whole pregnancy. However, only FPG in the 3


While the age at first tooth eruption was older in identical twins who were breastfed for the first 6 months, this increase was not observed in DZ twins. The mean of ETFPT was calculated as 7.31 months in MZ twins and 6.75 months in DZ twins. The effect of breastfeeding and birth weight on ETFPT may differ according to zygosity in twins. MZ twins may tend to take longer to experience the eruption of their first primary teeth.The timing of primary tooth eruption is critical for children’s health planning and the diagnosis of specific growth disorders. The purpose of this study is to assess the relationship between twin pairs’ birth weight, gestational age, and gender, which are indicators of prenatal factors; breast-feeding duration, which is an indicator of postnatal factors; type of delivery, which is an indicator of maternal as well as genetic factors; and age of the primary tooth. Twin children aged from 3 to 15 years who applied to the clinic for the first dental examination constituted the sample group. In this twin study, 59 monozygotic (MZ) twin pairs and 143 dizygotic (DZ) twin pairs were included. Genetic (MZ vs. DZ), maternal , perinatal , and postnatal (duration of breastfeeding) information was obtained, and effects on the children’s Eruption Timing of the First Primary Tooth (ETFPT) were examined. Statistical analysis was performed using the consistent partial least squares structural equation model (robust PLSc) technique. As birth weight increased, the age at first eruption became younger, but this change was different between MZ and DZ twins ( Tooth eruption is the progressive migration of a tooth from the alveolar bone’s developing zone to the location where it will function in the mouth and the occlusal plane . Tooth ePreterm birth, which is one of the perinatal factors, can affect the child’s oral growth and development . Many stDelivery is one of the maternal factors affecting tooth development. The neonatal line is accepted as an indicator of birth and is formed as a result of a disruption in mineralization reflecting physiological trauma at birth . It has The present study was undertaken to determine whether the relationships among prenatal, postnatal, and maternal factors and age at the time of eruption of primary teeth differ between monozygotic (MZ) and dizygotic (DZ) twin pairs. This study explores the effects of gestational age, gender, birth weight, breastfeeding duration, mode of delivery, and zygosity on the eruption time of the first primary tooth (ETFPT).In this twin study, it was intended to assess the relationships among maternal, perinatal, and postnatal components as well as genetic factors and ETFPT among twin siblings.The study sample comprised only MZ and DZ pairs of twins between the ages of 3 and 15 years, who applied to the pedodontic clinic of Istanbul University, Faculty of Dentistry, for an oral examination during 2014–2017 without any systemic or genetic diseases, mental problems, or previous orthodontic treatments. Triplets and quadruplets were not included in this study.The Istanbul University, Istanbul Faculty of Medicine Clinical Research Ethics Committee granted ethical approval with Approval Code 592 in accordance with the Helsinki Declaration.The zygosity status of all twin pairs was initially recorded according to the anamnesis information obtained from the families. Twins with different genders were automatically accepted as DZ twins. Zygosity was subsequently confirmed for 100 selected pairs of the same gender by analyzing 16 Short Tandem Repeat (STR) markers using the AmpFLSTR Identifiler Polymerase Chain Reaction (PCR) Amplification Kit  and subsequent fragment analysis. Out of 100 selected twin pairs, 34 were monozygotic and 66 were dizygotic. The final study sample included 149 pairs of MZ twins and 59 pairs of MZ twins who visited our clinic for their first dental examinations. The participants’ families signed written, voluntary, informed permission forms on behalf of both themselves and their kids.During the oral examination of the twins participating in the study, data on the type of delivery, birth weights, gestational age, ETFPT, and duration of breastfeeding were collected from their parents using a detailed questionnaire.The children’s birth weights and gestational ages were categorized using the relevant World Health Organization standards ,22,23.For gestational age at birth, there were two categories: low gestational age (less than 37 weeks) and normal gestational age (at least 37 weeks). Moreover, perinatal information was gathered, including the gender and weight of the infants. The three categories used to classify birth weight were low birth weight (2500 g), normal birth weight (2500–4000 g), and macrosomia (>4000 g).ETFPT was evaluated within three groups: early eruption time (<6 months), normal eruption time (6–8 months), and late eruption time (>8 months) ,23. The Data were obtained from 404 individuals in 2 groups: the MZ and DZ twin groups. Multivariate statistical analyses were performed in the SmartPLS 3 package program, and descriptive statistics and graphics were prepared in the IBM SPSS Statistics 26  package program.The Partial Least Squares Structural Equation Model (PLS-SEM) technique was applied to the research model we designed . The hypThe tested hypotheses are:Hypothesis 1.There is a statistically significant relationship between zigosity and the ETFPT;Hypothesis 2.There is a statistically significant relationship between pregnancy and term (ETFPT);Hypothesis 3.There is a statistically significant relationship between gender and the ETFP;Hypothesis 4.There is a statistically significant relationship between breastfeeding and the ETFPT;Hypothesis 5.There is a statistically significant relationship between birth weight and the ETFPT;Hypothesis 6.There is a statistically significant relationship between the type of delivery and the ETFPT;Hypothesis 7.Zygosite has a moderating role in the relationship between pregnancy and term (ETFPT);Hypothesis 8.Zygosite has a moderating role in the relationship between breastfeeding and the ETFPT;Hypothesis 9.Zygosite has a moderating role in the relationship between birth weight and the ETFPT;Hypothesis 10.Zygosite has a moderating role in the relationship between the type of delivery and the ETFPT.Total effects were analyzed with the consistent PLS bootstrapping algorithm , and corThe heterotrait-monotrait ratio (HTMT) criterion is one of the methods recommended for assessing the discriminant validity of PLS-SEM models. Discriminant validity has been established if the HTMT values of the variables are less than 0.90 . The HTMTherefore, the model provides discriminant validity. On the other hand, it was observed that all variance inflation factors (VIF) were below 10 .Accordingly, there were no problems with multicollinearity in the model . Since tA total of 404 twin siblings (202 pairs of twins) were enrolled in this study, including 204 boys and 200 girls. A total of 286 DZ twin pairs (70.8%) and 118 MZ twin pairs (29.2%) were examined genetically. The chronological ages of the siblings ranged from 3 to 15 years, with a mean age of 8.77 ± 3.22 years. ETFPT ranged from 0 months  to 24 months of age, with a mean of 6.92 ± 2.35 months .p = 0.003)  .p = 0.043)  .MZ and DZ twins were coded as 0 and 1 for the zygosity variable, respectively, and so the obtained coefficient of 0.286 shows a positive effect for DZ twins. Therefore, the negative relationship between birth weight and ETFPT was stronger for MZ twins than it was for DZ twins .p = 0.001), it was not significant in DZ twins (p = 0.275)  . The f2 p = 0.219) (p = 0.029)  . However= 0.029) .The mean ETFPT was 6.52 months of age among MZ twins who were not breastfed for the first 6 months, and this value increased to 7.86 months for those who were breastfed for the first 6 months. Such an increase was not observed among DZ twins. While the mean ETFPT was 6.96 months of age among DZ twins who were not breastfed for the first 6 months, this value was 6.72 months for those who were breastfed for the first 6 months .p = 0.019), the decrease in DZ twins was not significant (p = 0.422). The f2 value of breastfeeding was calculated as 0.027 for MZ twins and 0.003 for DZ twins. In addition, the total effect of zygosity on ETFPT in the model was statistically significant  (While the increase in ETFPT according to breastfeeding was significant in MZ twins (= 0.026) .2 value of zygosity was 0.015 for the entire study sample, including both MZ and DZ twins. No statistically significant relationship existed between gender or the length of the pregnancy and the ETFPT (p > 0.05). Likewise, no moderating effect of zygosity was found between type of delivery mode or pregnancy duration and ETFPT (p > 0.05).While the mean of ETFPT for MZ twins was determined to be 7.31 months, this value was 6.75 months for DZ twins. The fTo investigate the influence of genetic variables on tooth eruption, the eruption periods of primary teeth in terms of zygosity were compared among pairs of twins in this study. At the same time, the potential moderating effects of zygosity on other factors that may affect tooth eruption were also evaluated, differently from other studies. It was found that ETFPT values were much closer to each other in MZ twin pairs. In addition, the effect of birth weight on tooth eruption times was stronger among MZ twins. This suggests that other factors exert stronger effects by reducing the impact of genetic factors on tooth eruption in MZ twins with higher genetic similarity ratios.In this study, it was also seen that gender had no effect on ETFPT. In previous studies examining the effect of gender on differences in tooth eruption, conflicting findings were reported, with different studies reporting that tooth eruption was earlier in girls or boys ,10. TherThe results of our study suggest that birth weight affects tooth development in the prenatal period and has an effect on the eruption timing of the primary tooth. Prenatal and postnatal nutrition are both important for the maturation of tooth enamel , and thePremature birth can negatively affect tooth development and cause delayed tooth eruption in infants ,18,19. AStudies on the type of delivery, which is one of the maternal factors, have mostly focused on enamel development ,34,35. IAs a result of our analyses, no direct effect of breastfeeding for the first 6 months on ETFPT was observed for the entire study sample. However, when the children were evaluated according to zygosity status, zygosity was found to affect the relationship between postnatal nutrition and tooth eruption age. There was a relationship between breastfeeding duration and ETFPT among MZ twins, but such a relationship was not seen in the DZ group. This suggests that among DZ twins with more genetic differences, genetic factors have a greater effect on ETFPT as well as the duration of breastfeeding. When the path coefficients were examined, it was seen that the coefficient of the moderator effect of zygosity on the effect of birth weight (B = 0.286) was higher than the coefficient (B = −0.200) for the effect of the breastfeeding variable. Contrary to our study findings, Alnemer et al.  reportedThe current investigation has a number of limitations. The use of supplements such as vitamin D and other vitamins was not evaluated within the category of nutrition. Another limitation is the fact that the effect of the amount of breast milk received by the infants according to percentiles could not be considered. Previous studies have also found earlier ETFPT in children born to mothers who smoked while they were pregnant, but this study did not evaluate the mothers’ habits, such as smoking during pregnancy. Furthermore, effects of other factors such as socioeconomic factors, maternal education level, and general maternal health were not examined here.The contributions of this study to the literature can be listed as follows. First of all, this was a twin study in which genetic similarity was examined together with other factors of interest. This study was able to strengthen the causality among different factors by evaluating variables related to prenatal, postnatal, maternal, genetic characteristics, and ETFPT. Tooth eruption is clinically important for a child’s growth and development, the management of the occlusions, and treatment planning. Even if variations in eruption times are small, they may provide guidance for clinicians considering the factors that may affect the growth and development of children, and they may also shed light on conditions such as eruption problems and developmental diseases that may occur in the future. Therefore, it is important to investigate different determinants that may affect ETFPT.In conclusion, the effects of breastfeeding and birth weight on ETFPT may differ according to zygosity in twins. MZ twins may tend to take longer to experience eruptions of their first primary teeth.Birth weight affects tooth development in the prenatal period and has an effect on ETFPT;The variation of the eruption age according to birth weight was much more pronounced among MZ twins;A moderating effect of zygosity was found between breastfeeding and ETFPT.Bullet points:


Maternal voice intervention induced a significant reduction in cortisol and an increase in OT levels in mothers when the maternal voice with a tactile stimulation intervention was performed first. In conclusion, exposure to the maternal voice with a contingent tactile stimulation was associated with subtle changes in the maternal hormonal balance between OT and cortisol. These findings need to be confirmed in a larger sample size and may ultimately guide caregivers in providing the best intervention to reduce parental stress following preterm delivery.Prematurity is a major risk factor for perinatal stress and neonatal complications leading to systemic inflammation and abnormal mother–infant interactions. Oxytocin (OT) is a neuropeptide regulating the inflammatory response and promoting mother–infant bonding. The release of this hormone might be influenced by either vocal or tactile stimulation. The main objective of the current randomized, crossover, clinical trial was to assess the salivary OT/cortisol balance in mothers following the exposure of their baby born preterm to two types of sensorial interventions: maternal voice without or with contingent tactile stimulation provided by the mother to her infant. Among the 26 mothers enrolled, maternal voice intervention alone had no effect on OT and cortisol levels in the mothers, but when associated with tactile stimulation, it induced a significant increase in maternal saliva oxytocin (38.26 ± 30.26 pg/mL before vs 53.91 ± 48.84 pg/mL after,  Prematurity is a major risk factor of neurocognitive impairment and neurobehavioral disorders during infancy and in adults . While tThe beneficial effects of exposure to the maternal voice on the physiological and behavioral constants of hospitalized stressed preterm infants were demonstrated ,7, but tEarly multisensory interventions in the NICUs improved several aspects in infants’ development and reduced maternal stress, but not all findings were consistent . PrematuIn the neonatal period, the optimal conditions of exposure to human voice, live or recorded, of hospitalized preterm infants are not yet clearly established. Previous research showed that the presence of a recorded female voice interfered with tactile sensory learning in preterm human infants . The autThe primary objective of this research was to investigate if a live maternal voice was associated with changes in OT and cortisol saliva concentrations in mothers of preterm infants and if a concomitant tactile stimulation would modulate this hormonal response.We conducted a randomized, crossover, monocentric, unmasked clinical trial (NCT04665440) that enrolled 28 mothers who delivered neonates between 32 and 35 weeks’ gestation. Infants were aged from 5 to 12 days at the interventions and were free of morbidities or respiratory support. For multiple pregnancies, the mother was investigated only once, and interventions were applied to the first newborn. The study was approved by the Geneva Research Ethics Committee (BASEC No. 2020-00101) and was audited by the clinical research center, University Hospitals Geneva. A written consent was collected from the parents of each infant. Data on maternal characteristics and pregnancy events were extracted from the clinical database of the perinatal center. Maternal characteristics included demographic data, the main cause of preterm delivery, antenatal steroids, and delivery route. Neonatal characteristics of the infant included the sex, gestational age at birth, birth weight, intra-uterine growth restriction (defined as birth weight < 10th percentile), APGAR score at 5 min, and potential complications of preterm birth that occurred before the interventions. Early onset sepsis (EOS) was defined as the association of biological signs and clinical deterioration, with or without bacteriological documentation before 48 h of life. Transient tachypnea of the newborn was defined as supplemental oxygen or respiratory support for less than 72 h after birth.In this crossover trial, the infants of the recruited mothers were exposed to two interventions whose order was randomly allocated and performed once in the afternoon during two consecutive days : maternaFor the maternal voice intervention (V), the mother was free to choose the contents and the language of her speech (minimum 10 dBA above the background noise).For the intervention combining the maternal voice and a third-party tactile stimulation (VT), the experimenter was standing on the other side of the incubator facing the mother, out of the field of the infant’s vision. While the mother spoke to her infant, the experimenter placed a wooden object (prism or cylinder) in the infant’s hand . When tIn a previous study , a samplHere, under baseline conditions (without any painful procedure), we primarily hypothesized that the effect of a maternal voice on the OT saliva concentration in mothers will be similar. Considering the hypothesis that tactile stimulation of the baby may attenuate this effect by 50%, a total of 80 participants should be recruited. Taking into account the missing data and dropped out, we planned to include 84 children in total, i.e., 42 children per group.The primary objective of this research was planned to investigate if a live maternal voice was associated with changes in saliva concentrations of cortisol and OT in preterm infants and their mothers. The secondary objective was to assess if a concomitant tactile stimulation would modulate this hormonal response in the mother–neonate dyads.The primary outcomes were planned to be biological measurements of saliva OT and cortisol for both the mother and the newborn. Due to technical issues in collecting an appropriate volume of the infant’s saliva, maternal samples only were processed. Maternal saliva (500 µL) was collected at a distance (>2 h) of foods with high sugar, acidity, or caffeine before and 10–15 min after each intervention. Following passive drool into a validated collection device, samples were placed on wet ice immediately, and frozen and stored at −20 °C within 30 min. Saliva OT was measured in triplicate by quantitative electrochemoluminescence with a sensitivity of 4 pg/mL (assay range of 8–1000 pg/mL) by Salimetrics . Saliva cortisol was measured in duplicate by enzyme immune assay with a sensitivity of less than 0.007 µg/dL (assay range of 0.012–3.000 µg/dL).The mothers were invited to fill in a questionnaire just before the first intervention and just after the second intervention. The questionnaire was the Parental Stressor Scale Neonatal Intensive Care Unit . It incp-value < 0.05 was considered significant. Statistical tests were run on GraphPad Prism version 9.00 .Qualitative variables were described as frequencies (percentages) and quantitative variables as mean (standard deviation) and median (first–third quartiles [IQR]). Group comparisons were computed using either Fisher’s exact test for qualitative variables and Mann–Whitney tests for quantitative variables. Non-parametric Wilcoxon–Mann–Whitney paired tests were used for comparing quantitative biological variables between two groups. When comparing more than two groups, either a Kruskal–Wallis or a Friedman test of repeated measures of one-way ANOVA was used, followed by a Dunn’s multiple comparisons test when appropriate. Because the first intervention may affect the result of the second intervention, the carryover effect was addressed using a mixed-effects model for both OT and cortisol changes before and after intervention, according to the sequence used (V then VT or VT then V). The effect of the sequence randomly assigned to the subjects and sequence x intervention interaction were tested. For all analyses, The flow chart of the study is described in the V then VT means that maternal voice alone was performed the first day and maternal voice with a third-party tactile stimulation the day after.VT then V means maternal voice with a third-party tactile stimulation was performed the first day and maternal voice alone the day after.OT means oxytocin.Cort means cortisol.Twelve mothers were assigned to the group for which the vocal intervention alone should be conducted first, and fourteen assigned to the group for which intervention combining vocal exposure and tactile stimulation should be conducted first. Characteristics of the studied population are described in p = 0.02), particularly in the mothers who delivered a female neonate. Cortisol levels were found to be similar before and after the combined intervention, independently of the sex of the newborn.We first assessed the ability of each intervention to induce changes in saliva concentrations of cortisol and OT in the mothers. Next, we studied a potential carryover effect induced by the crossover design by assessing hormonal changes according to the order of each intervention. p = 0.048) and an increase in OT level  was observed when maternal voice without tactile stimulation was performed on Day 2  and for cortisol .In addition, the period effect (V then VT vs. VT then V) and the period x intervention effect interaction were assessed using mixed-effects models for both OT and cortisol. These analyses failed to demonstrate any significant effect of either period or interaction for OT . PSS-NICU provides an overall stress score and subscores focused on sights and sounds in the NICU (S1), infant appearance and behavior (S2), and parent role restriction (S3). No significant difference was observed among these scores and subscores, before and after the interventions A,B. HoweThis study reveals subtle changes in hormonal balance in mothers talking to their preterm baby in the stressful context of the NICU, with a notable increase in OT concentration in saliva when the maternal voice was associated with contingent tactile stimulation. Randomization of this trial appears to be quite balanced, but postnatal age at discharge significantly differs. This difference may be a consequence of the slightly lower gestational age at birth in the group with late hospital discharge and is certainly not a direct result of the interventions.Despite an abundant literature on the role of socio-emotional environment and parental interactions in the neurodevelopmental outcomes of infants born preterm , only a Our findings are of interest to identify the optimal conditions of exposure to the human voice for hospitalized preterm infants. Indeed, exposure to a recorded female voice, other than the maternal voice, in preterm infants was shown to impair their handling of tactile abilities , suggestMoreover, the increase in maternal OT for the intervention including maternal voice and a contingent tactile stimulation was observed only for mothers of girls. This finding is in line with a recent paper showing that parvocellular OT neurons are primarily activated by somatosensory stimuli, transmitted to the larger population of magnocellular neurons, and consequently show coordinated increases in their activity during social interactions between virgin female rats . This seBiological measurements of OT and cortisol were the primary outcomes of the present study because OT was shown to balance cortisol release in response to stress ,31. In aA recent study reported that salivary OT levels significantly increased from late pregnancy to 1 day postpartum and then decreased until 5 days postpartum, a decrease associated with maternity blues, postpartum fatigue , and thaThis study has several limitations. First, the sample size initially planned was not reached due to recruitment issues. Indeed, besides the COVID crisis that occurred during the recruitment phase, we did not anticipate that a substantial proportion of eligible subjects would not be French-speaking and that many infants would be transferred to another hospital early after birth. In addition, there was a relatively large proportion 40%) of parents who did not consent. The early termination of the trial reduced the ability to achieve adequate power for the study, which limits our ability to assess the effect of maternal voice on OT concentration and obviously precludes any definitive conclusion regarding the effect of a concomitant tactile stimulation. Second, only maternal samples met requirements for OT measurements because saliva volumes collected in neonates were too small. Dyad analyses of saliva hormonal changes were therefore not feasible. Third, some issues with OT measurement in saliva may relate to the reliability and accuracy of the method used. Indeed, the concentration of OT in saliva is relatively low, leading to potential inconsistencies in results, and other factors, such as the timing of sample collection, sample handling, and storage conditions, can significantly impact the measured OT levels. Some authors claimed that salivary OT has only little or no correlation with cerebrospinal fluid, as well as little relevance in terms of physiological function ,54. Conv% of pareIn conclusion, this study provides preliminary evidence that live maternal voice intervention to their preterm infants may influence hormonal balance in mothers towards higher OT/cortisol ratio under certain experimental conditions. These findings need to be confirmed in a larger sample size and correlated with the hormonal effect of these interventions on hormonal regulation in the neonate and ultimately on their neurodevelopmental outcomes.