Maternal thyroid disease in pregnancy and timing of pubertal development in sons and daughters

OBJECTIVE

To study whether maternal thyroid disease in pregnancy is associated with pubertal timing in sons and daughters.

DESIGN

Cohort study.

SETTING

National birth cohort and health registers.

PATIENT(S)

A total of 15,763 mothers and children from the Danish National Birth Cohort and its Puberty Cohort.

INTERVENTION(S)

Register-based and self-reported information on maternal thyroid diseases during pregnancy (hyperthyroidism, hypothyroidism, benign goiter, or no thyroid disease [reference group]).

MAIN OUTCOME MEASURE(S)

The adjusted mean age difference (months) at attaining several self-reported pubertal milestones collected every 6 months using an interval-censored regression and the average difference in age at attaining all pubertal milestones using the Huber-White robust variance estimation (primary outcome).

RESULT(S)

Sons of mothers with hyperthyroidism had earlier pubertal development (average difference, -2.9 [95% confidence interval (CI), -5.0 to -0.7] months) than unexposed sons. Maternal hypothyroidism was not associated with pubertal development in sons (average difference, -1.2 [95% CI, -5.1 to 2.7] months). We observed nonstatistically significant indications of earlier pubertal development in sons of mothers with benign goiter (average difference, -1.9 [95% CI, -4.6 to 0.9] months). Maternal thyroid disease was not associated with pubertal development in daughters (average difference (months), hyperthyroidism, -0.8 [95% CI, -2.8 to 1.2]; hypothyroidism, 0.3 [95% CI, -3.1 to 3.8]; and benign goiter, 0.7 [95% CI, -2.0 to 3.4]).

CONCLUSION(S)

We found indications of earlier pubertal development in sons of mothers with hyperthyroidism. More research is needed to further investigate the observed sex-specific association.

Timing of Pubertal Development in Boys and Girls With Congenital Heart Defects: A Nationwide Cohort Study

Background

Children with congenital heart defects (CHD) have an increased risk of developmental delay. It remains sparsely investigated if these patients also have a delayed pubertal development. In this nationwide cohort study, we evaluated if CHD was associated with timing of puberty using longitudinally collected data on pubertal milestones.

Methods and Results

We used data from the Danish nationwide Puberty Cohort. Information on CHD was obtained from the Danish National Patient Register. Information on pubertal development was obtained from 15 780 children through questionnaires answered half‐yearly from 11 years until 18 years or full maturity. Using a multivariable regression model for censored time‐to‐event data, mean difference in age at attaining each pubertal milestone was estimated, including a combined pubertal marker. Compared with children without CHD, analyses were performed for both CHD overall and subdivided into simple and complex CHD. In a subanalysis, analyses were repeated in children born at term. In total, 137 children (62 boys and 75 girls) had a CHD diagnosis. Overall, no difference in age at pubertal timing was observed for children with CHD compared with unaffected children. The average differences were small for both boys (1.6 [95% CI, −2.6 to 5.7] months) and girls (1.0 [95% CI, −2.5 to 4.4] months). The same differences were observed when subdividing into simple or complex CHD and when restricting to children born at term.

Conclusions

We found no association between CHD and pubertal timing. For the group of children with complex CHD, we were unable to exclude a later pubertal timing.

Parental Separation and Semen Quality in Young Men: A Population-Based Cohort Study

Purpose

Parental separation may be a stressful life event with the potential to influence hormonal regulation of offspring reproductive health and thereby affect semen quality in young men. We aimed to study the association between parental separation in pregnancy or in childhood and semen quality in young men and to study whether the timing of parental separation in childhood was important.

Patients and Methods

We conducted a follow-up study of 1058 young men born 1998–2000 from the Fetal Programming of Semen Quality (FEPOS) cohort nested within the Danish National Birth Cohort. Data on parental separation were obtained longitudinal by self-report. Parental separation in pregnancy was dichotomized, and parental separation in childhood was both dichotomized and categorized according to the timing of parental separation (from birth, from early childhood (0–5 years), and from late childhood (6–10 years)). Semen volume, concentration, total sperm count, motility, morphology, and testes volume were analysed using multivariable negative binomial regression models.

Results

Parental separation in pregnancy was not associated with semen quality. The association between parental separation in childhood and semen quality differed with the timing of parental separation. Parental separation from birth was associated with higher semen volume of 25%, 95% CI (−5; 64); higher total sperm count of 62%, 95% CI (−6; 179); and higher proportion of morphologically normal spermatozoa of 59%, 95% CI (20; 111). Parental separation in early childhood was associated with lower semen volume of −14%, 95% CI (−24; −3); lower concentration of −15%, 95% CI (−28; 1); lower total sperm count of −17%, 95% CI (−32; 2) and lower testes volume of −11%, 95% CI (−18; −3).

Conclusion

The timing of parental separation was important, and parental separation from birth was associated with higher semen quality, and parental separation in early childhood was associated with lower semen quality.

Caesarean delivery and pubertal timing in boys and girls: A Danish population-based cohort study

BACKGROUND

There is considerable public and scientific interest in the declining age of pubertal timing. Prenatal and postnatal stress has been proposed to relate with earlier pubertal timing, but it remains unknown whether intrapartum stress may affect pubertal timing as well.

OBJECTIVE

This study aims to examine the potential effect of caesarean delivery on pubertal timing in boys and girls.

METHODS

This study was based upon the nationwide Puberty Cohort nested within the Danish National Birth Cohort (DNBC) from 2000 to 2003. A total of 15,731 mother-child pairs with complete information on delivery mode and puberty were included in the main analysis. The delivery mode was categorised into non-instrumental vaginal delivery (reference), instrumental vaginal delivery, elective caesarean delivery before labour, emergency caesarean delivery during labour and un-specified caesarean delivery. Children's pubertal development were self-reported in web-based questionnaires from 11 years of age and every 6 months throughout puberty (2012-2019), including Tanner stages 2-5, menarche, voice break, first ejaculation, axillary hair growth and the onset of acne. Regression models for censored, normally distributed time-to-event data were used to estimate mean monthly differences in age at attaining the different pubertal milestones and the average of all these estimates for each sex (a combined indicator of pubertal timing).

RESULTS

A total of 2810 participants were born by caesarean delivery (17.9%). Neither elective nor emergency caesarean delivery was associated with earlier age at achieving the pubertal milestones in boys or in girls. For the combined indicator, the mean age differences for elective caesarean delivery and emergency caesarean delivery were 0.1 (95% CI -1.1, 1.4) months and -0.7 (95% CI -2.0, 0.5) months in boys and 0.7 (95% CI -0.7, 2.0) and 0.2 (95% CI -1.3, 1.7) in girls.

CONCLUSIONS

This study does not suggest a clinically important effect of caesarean delivery on children's pubertal timing.

Use of paracetamol (acetaminophen) as a nonprescription analgesic and semen quality in young men: A cross-sectional study

BACKGROUND

Paracetamol (acetaminophen) is a frequently used nonprescription analgesic with suggested endocrine-disrupting properties. Epidemiological evidence on the effect of paracetamol on male fecundity is sparse.

OBJECTIVES

To investigate if the use of paracetamol as an oral nonprescription mild analgesic was associated with semen quality in young men.

MATERIALS AND METHODS

This cross-sectional study was based on data from the Fetal Programming of Semen Quality (FEPOS; 2017-2019) cohort of 1058 young men (18-21 years) included in the Danish National Birth Cohort. Participants completed a comprehensive online questionnaire on health behavior including analgesic use and provided a semen sample. Negative binomial regression models were used to estimate the percentage differences (adjusted mean ratios [aMR]) in semen quality characteristics according to paracetamol use (no; yes) and frequency of use (almost never; <1/month; ≥1/month; ≥1/week).

RESULTS

In total, 28% of the 913 participants with available data reported the use of paracetamol within the last 6 months. We found a slightly higher total sperm count (aMR 1.13 95% CI [0.99-1.30]) in users compared to nonusers but other semen characteristics were unaffected. The frequency of use was suggestive of lower total sperm count and morphologically normal sperm cells primarily among users ≥1/week, however, CIs were wide.

DISCUSSION

We were unable to account for the underlying reason for paracetamol use, which may induce confounding by indication. Exposure misclassification due to recall is likely but probably nondifferential due to the participants' young age and unawareness of semen quality. Due to the rapid plasma half-life of paracetamol and few frequent users, it was not possible to conclude on potential high-dose effects.

CONCLUSION

Our findings do not suggest any strong detrimental effect of paracetamol use on semen quality within this sample of young Danish men. However, the effects of high dose and frequent use cannot be excluded.

Nausea During Pregnancy and Timing of Pubertal Development in Sons and Daughters: A Population-Based Cohort Study

PURPOSE

The objective of this study was to explore whether maternal nausea in pregnancy, a potential surrogate marker of endogenous estrogen levels, was associated with age at attaining pubertal milestones in sons and daughters.

MATERIALS AND METHODS

The study included a total of 14,612 boys and girls born in 2000-2003, from the Danish National Birth Cohort. Information on nausea was reported by mothers during pregnancy in telephone interviews scheduled around gestational week 12 and 30. Their children were invited every six months from 11 years of age until 18 years of full maturation to provide information on current pubertal status. Pubertal milestones included pubic hair, axillary hair and acne for both sexes, besides genital development, voice break and first ejaculation for boys, and breast development and menarche for girls. Mean monthly differences in age at attaining several pubertal milestones for boys and girls were estimated according to duration of nausea in the first trimester (0, 1-6, 7-11, 12 weeks). Further, we explored whether duration of nausea in the first two trimesters (0, 1-8, 9-15 or 16-28 weeks) and severity (measured by co-existence of vomiting and weight loss) were associated with pubertal timing.

RESULTS

Neither maternal nausea in the first trimester nor duration or severity of nausea in the first two trimesters were associated with pubertal timing.

CONCLUSION

Our study does not support the hypothesis that nausea in pregnancy - as a surrogate marker of endogenous estrogen levels - is associated with age at attaining pubertal milestones in children.

Breast feeding and timing of puberty in boys and girls: A nationwide cohort study

BACKGROUND

Breast feeding has been associated with improved infant health, but its impact on pubertal timing remains uncertain, particularly in boys.

OBJECTIVE

The objective of this study was to investigate the association between duration of breast feeding and pubertal timing in boys and girls.

METHODS

This population-based cohort study included 13 511 boys and girls from the Puberty Cohort nested within the Danish National Birth Cohort. The children gave half-yearly, self-reported information on pubertal development through questionnaires (Tanner stages, age at menarche, first ejaculation, voice break, axillary hair growth, and acne). Information on breast feeding was provided by the mothers when the children were 6 months of age. We estimated mean differences (in months) in age at attaining each pubertal marker and for overall timing of puberty (combined estimate) for every additional month of exclusive breast feeding. Furthermore, we estimated differences in pubertal age when comparing children never exclusively breastfed and exclusively breastfed <4 months using children exclusively breastfed ≥4 months as reference. In sub-analyses, we further adjusted for infant weight gain and childhood BMI at 7 years to investigate whether these variables mediated the association.

RESULTS

Boys tended to reach pubertal markers later for every additional month of exclusive breast feeding (combined estimate: 0.2 (95% confidence interval [CI] 0.0, 0.4 months). Never exclusively breastfed boys reached pubertal markers earlier than the boys exclusively breastfed ≥4 months (combined estimate: -4.1 (95% CI -6.7, -1.6) months). Boys exclusively breastfed <4 months also reached pubertal markers earlier than those never exclusively breastfed but with smaller differences. In girls, duration of breast feeding was not associated with pubertal development. When including infant weight gain or childhood BMI, the results remained essentially unchanged.

CONCLUSIONS

Shorter duration of exclusive breast feeding was associated with earlier pubertal development in boys but not in girls.

The influence of parental age on timing of puberty: A study in the Danish National Birth Cohort

Aims: Concerns have been raised about the potential negative biological effect of postponed parenthood upon the health of subsequent generations, including reproductive health. This study aimed to estimate if high parental age at birth was associated with accelerated pubertal timing in offspring. Methods: In this large-scale cohort study, 15,819 children born by mothers in the Danish National Birth Cohort from 2000 to 2003 participated in a nationwide puberty cohort (participation rate 71%). Between 2012 and 2018, the children reported half-yearly information on pubertal status using web-based questionnaires from 11 years throughout puberty or 18 years of age. Information on parental age was drawn from nationwide registers. We estimated adjusted mean differences in months for age at attaining the pubertal milestones and pubertal timing overall between the pre-specified parental age groups: 20-29 (reference), 30-34 and advanced parental age groups (35-44 years for mothers and >35 years for fathers). Results: Overall, parental age at birth of the child was not associated with pubertal timing in daughters or sons. For sons of older fathers (>35 years), we observed indications towards slightly earlier pubertal timing in the range of 0.3-2.4 months for nearly all pubertal milestones, but all confidence intervals were wide, and many included the null. Conclusions: We found no strong association between parental age and timing of puberty, and we find it unlikely that the decreasing age in pubertal timing is a result of parental decision to delay childbearing.

Hypertensive disorders in pregnancy and timing of pubertal development in daughters and sons

STUDY QUESTION

Do maternal hypertensive disorders affect pubertal development in daughters and sons?

SUMMARY ANSWER

Pubertal development tended to occur earlier in daughters of mothers with 'preeclampsia, eclampsia or HELLP syndrome' (hemolysis, elevated liver enzymes and low blood platelets) or hypertension in pregnancy compared to daughters born of normotensive mothers.

WHAT IS KNOWN ALREADY

The existing literature suggests some or no association between preeclampsia and pubertal development in daughters, but not in sons. None of the previous studies has investigated the possible association between other types of hypertensive disorders (hypertension, eclampsia or HELLP syndrome) and pubertal timing in children.

STUDY DESIGN, SIZE, DURATION

Longitudinal cohort study consisting of 15 819 mother-child pairs with information on maternal hypertensive disorders collected during pregnancy and information on pubertal development collected half-yearly from the age of 11 years and until fully developed or 18 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants are children from the Puberty Cohort nested within the Danish National Birth Cohort. The exposure was register-based and self-reported information on maternal hypertensive disorders during pregnancy. The outcomes were children's self-reported information on pubertal development, including Tanner stage 1-5 (pubic hair (both daughters and sons) and breast development (daughters) or genital development (sons)), first menstrual bleeding (daughters) or first ejaculation (sons), voice break episode (sons), axillary hair development and acne occurrence (both daughters and sons). The main outcome was mean difference in age at attaining each pubertal milestone and a combined pubertal marker in children of mothers with hypertensive disorders in pregnancy (either hypertension (n = 490), 'preeclampsia, eclampsia or HELLP syndrome' (n = 419) or 'unspecific hypertensive disorders' (n = 334) with unexposed children as reference (n = 14 576)).

MAIN RESULTS AND THE ROLE OF CHANCE

In daughters of mothers with 'preeclampsia, eclampsia or HELLP syndrome', we observed tendencies of earlier pubertal timing (combined marker: -2.0 (95% CI: -3.9; 0.0) months). In daughters of mothers with hypertension, several pubertal milestones tended to occur earlier than in daughters of normotensive mothers; however, all 95% CIs overlapped the null resulting in a combined pubertal marker of -1.0 (95% CI: -3.2; 1.1) months. In sons of mothers with any of the hypertensive disorders, we observed no difference in pubertal timing (combined markers: 'preeclampsia, eclampsia or HELLP syndrome': 0.1 (95% CI: -2.0; 2.1) months; hypertension: -0.6 (95% CI: -2.3; 1.1) months; 'unspecific hypertensive disorders': 0.2 (95% CI: -1.9; 2.2) months).

LIMITATIONS, REASONS FOR CAUTION

The study is subject to non-differential misclassification of self-reported information on maternal hypertensive disorders in pregnancy and current pubertal status; possibly causing bias toward the null.

WIDER IMPLICATIONS OF THE FINDINGS

Hypertensive disorders in pregnancy might accelerate pubertal timing in daughters; however, more studies are needed for causal conclusions.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Faculty of Health at Aarhus University. The authors have no financial relationships or competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Placental weight Z-score and pubertal timing: A population-based cohort study

BACKGROUND

The placenta provides nutrients, oxygen, and hormonal support for adequate fetal growth and development of the hormonal axes, which are important for pubertal timing later in life.

OBJECTIVES

We investigated if an indicator of poor placental function, low gestational age-specific Z-score for placental weight at birth, was associated with earlier pubertal timing.

METHODS

The study is based on a population-based cohort of 15 195 singleton boys and girls (68% of 22 439 invited) born 20 to 43 weeks of gestation (2000-2003) nested within the Danish National Birth Cohort. Placental Z-score was estimated from data collected at birth. Between 2012 and 2018, the children returned half-yearly web-based questionnaires from age of 11 years on status of the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne, and axillary hair. We estimated adjusted monthly differences in mean age at attaining the pubertal milestones and pubertal timing overall with placental Z-score continuously and as restricted cubic splines. Further, we explored whether growth by birthweight Z-score and body mass index Z-score around 7 years mediated the associations.

RESULTS

Placental Z-score was positively associated with age at attaining most of the pubertal milestones in girls, particularly for age at menarche, but not in boys. Effect sizes were modest, and when combining all pubertal milestones, one standard deviation increase in placental Z-score was associated with 0.5 months (95% confidence interval [CI] 0.2, 0.9) later pubertal timing overall in girls. The associations in girls were largely mediated through fetal growth.

CONCLUSIONS

Assuming that placental Z-score correlates with placental function, these findings suggest that placental dysfunction (low placental Z-score) advances pubertal timing in girls slightly by reducing fetal growth. Future studies need to evaluate whether placental weight sufficiently captures intrauterine growth of importance for pubertal development and search for other potential candidates reflecting placental function.

Father Absence in Pregnancy or During Childhood and Pubertal Development in Girls and Boys: A Population-Based Cohort Study

This cohort study, including 15,810 children born 2000-2003 in Denmark, aimed to investigate the association between father absence in pregnancy or during childhood and pubertal development in girls and boys. The children were followed from 11 years of age and throughout pubertal development. Mean age differences according to exposure groups were estimated for each pubertal marker separately and for a combined pubertal marker. The results suggested that father absence in pregnancy and during childhood was associated with earlier pubertal development in girls, and father absence from late childhood was associated with earlier pubertal development in boys. The paternal investment theory, the psychosocial acceleration theory and the energetics theory were explored, and did not seem to explain the observed associations.

Risk of selection bias due to non-participation in a cohort study on pubertal timing

BACKGROUND

Non-participation in aetiologic studies of pubertal timing is frequent. However, little effort has been given to explore the risk and potential impact of selection bias in studies of pubertal timing.

OBJECTIVE

We aimed to explore the risk of selection bias due to non-participation in a newly established puberty cohort.

METHODS

We evaluated whether three maternal exposures chosen a priori (pre-pregnancy obesity, smoking, and alcohol drinking during pregnancy) were associated with participation, whether pubertal timing was associated with participation, and whether selection bias influenced the associations between these exposures and pubertal timing. In total, 22 439 children from the Danish National Birth Cohort born 2000-2003 were invited to the Puberty Cohort and 15 819 (70%) participated. Exposures were self-reported during pregnancy. Pubertal timing was measured using a previously validated marker, "the height difference in standard deviations" (HD:SDS), which is the difference between pubertal height and adult height, both in standard deviations. For this study, pubertal height at around 13 years in sons and around 11 years in daughters was obtained from an external database, and adult height was predicted based on parental height reported by mothers.

RESULTS

Participation was associated with most exposures but not with pubertal timing, measured by HD:SDS. The associations between exposures and HD:SDS were comparable for participants only and all invited for participation.

CONCLUSION

In conclusion, the risk of selection bias in aetiologic studies on pubertal timing in the Puberty Cohort appears minimal.

Timing of pubertal development in boys born with cryptorchidism and hypospadias: a nationwide cohort study

Pubertal development may be altered in boys with cryptorchidism and hypospadias, but existing knowledge is inconsistent. Therefore, we investigated the association between cryptorchidism and hypospadias and pubertal development in a large cohort study. Boys in the Puberty Cohort, a cohort nested within the Danish National Birth Cohort, were included in this study. Information on cryptorchidism and hypospadias was retrieved from the Danish National Patient Register. From 11 years until 18 years or full pubertal development, information on physical markers of pubertal development was provided biannually, including Tanner stages, axillary hair, acne, voice break, and first ejaculation. In multivariate regression models for interval censored data, the mean (95% confidence intervals [CIs]) differences in months in obtaining the pubertal markers between boys with and without the anomalies were estimated. Among 7698 boys, 196 (2.5%) had cryptorchidism and 60 (0.8%) had hypospadias. Boys with hypospadias experienced first ejaculation and voice break 7.7 (95% CI: 2.5-13.0) months and 4.5 (95% CI: 0.3-8.7) months later than boys without hypospadias. The age at attaining the Tanner stages for gonadal and pubic hair growth was also higher, though not statistically significant. Pubertal development seemed unaffected in boys with mild as well as severe cryptorchidism. In conclusion, hypospadias may be associated with delayed pubertal development, but pubertal development seems unaffected by cryptorchidism. The relation between hypospadias and later pubertal development may be due to the underlying shared in utero risk or genetic factors.

Childhood overweight and obesity and timing of puberty in boys and girls: cohort and sibling-matched analyses

BACKGROUND

Early puberty is a risk indicator for adult diseases. Identification of modifiable causes of earlier puberty is, therefore, warranted. We estimate the association between childhood body mass index (BMI) and pubertal timing in a cohort study and in a sibling-matched study to adjust for unobserved time-stable confounders shared within families.

METHODS

For the cohort study, 11 046 of 22 439 (49%) invited children, born 2000-203, from the Danish National Birth Cohort (DNBC) had information on childhood BMI at 7 years and self-reported, half-yearly puberty information from 11 years on Tanner stages, menarche, voice break, first ejaculation, acne, and axillary hair. For the sibling-matched study, 1700 brothers and sisters were included among 86 820 live-born singletons from the DNBC.

RESULTS

Childhood overweight (85th ≤ BMI < 95th percentile) and obesity (BMI ≥ 95th percentile) were associated with earlier age attaining the pubertal milestones in a dose-dependent manner in boys and girls. When modelling all pubertal milestones simultaneously, the pubertal milestones were attained earlier in: overweight boys: -3.1 [95% confidence interval (CI): -4.5, -1.7] months, overweight girls: -5.5 (95% CI: -7.1, -3.9) months, obese boys: -3.5 (95% CI: -5.1, -2.0) months, obese girls: -5.2 (95% CI: -7.1, -3.4) months compared with normal weight (BMI  < 85th percentile) children. In the sibling-matched study, higher BMI was associated with earlier age at attaining most pubertal milestones in girls, but only a tendency toward earlier pubertal timing was observed in boys.

CONCLUSIONS

Childhood overweight and obesity were associated with earlier pubertal timing even after adjustment for unobserved time-stable confounders shared within families.

Maternal pre-pregnancy obesity and timing of puberty in sons and daughters: a population-based cohort study

Background

In many countries, an increased prevalence of obesity in pregnancy has coincided with a declining pubertal age. We aimed to explore the potential effect of maternal pre-pregnancy overweight and obesity on timing of puberty in sons and daughters.

Methods

Between 2012 and 2018, 15 819 of 22 439 invited children from the Danish National Birth Cohort, born 2000–03, provided half-yearly information from the age of 11 years on the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne and axillary hair. We estimated adjusted mean monthly differences (with 95% confidence intervals) in age at attaining the pubertal milestones for children exposed to maternal pre-pregnancy obesity [body mass index (BMI) ≥30.0 kg/m²] or overweight (BMI 25.0 to 29.9 kg/m²) with normal weight (BMI 18.5 to 24.9 kg/m²) as reference. In mediation analysis, we explored whether childhood BMI at age 7 years mediated the associations.

Results

Maternal pre-pregnancy obesity was associated with earlier age at attaining most pubertal milestones in sons, and pre-pregnancy overweight and obesity were associated with earlier age at attaining all pubertal milestones in daughters. When combining all pubertal milestones, pre-pregnancy obesity [sons: −1.5 (−2.5, −0.4) months; daughters: −3.2 (−4.2, −2.1) months] and overweight [daughters only: −2.6 (−3.3, −1.8) months] were associated with earlier timing of puberty. The associations in sons were completely mediated by higher childhood BMI and partly so in daughters.

Conclusions

Maternal pre-pregnancy obesity appears to lower timing of puberty through childhood obesity in sons and mainly through other mechanisms in daughters.

Prenatal exposure to antibiotics and timing of puberty in sons and daughters: A population-based cohort study

OBJECTIVE

To investigate if prenatal exposure to antibiotics is associated with earlier timing of pubertal development in sons and daughters.

STUDY DESIGN

This population-based cohort study is based upon the Puberty Cohort and includes a sample of 15,638 children born 2000-2003 in Denmark. Information on maternal use of antibiotics was collected around gestational week 30 and 6 months postpartum. The children were followed-up half-yearly from 11 years of age and throughout sexual maturation providing information on Tanner stages, acne and axillary hair, in addition to voice break and first ejaculation in sons and menarche in daughters. Due to the half-yearly collection of data on pubertal timing, the data was censored and therefore analysed using a multivariable censored time-to-event regression model. We examined both prenatal exposure to antibiotics at any time in pregnancy and trimester-specific prenatal exposure to antibiotics and pubertal timing, adjusting for maternal baseline socioeconomic and lifestyle characteristics. Mean age differences for the pubertal milestones between exposure groups were estimated. A combined estimate for overall pubertal timing was calculated based on combining all pubertal milestones into one model for sons and daughters, using Huber-White robust variance estimation which handles the risk of type 1 errors due to multiple testing of correlated outcomes. An active comparator approach with restriction to women reporting to have a urinary tract infection (cystitis) treated with either penicillin or sulfonamides was employed in a sub-analysis.

RESULTS

The prevalence of any maternal use of antibiotics in pregnancy was 21.1 %. There was no association between prenatal exposure to antibiotics and timing of pubertal development for the individual milestones. The adjusted combined estimate for pubertal timing in sons prenatally exposed to antibiotics at any point in pregnancy was -0.4 (95 % confidence interval (CI): -1.2; 0.4) months compared to unexposed sons. The adjusted combined estimate for pubertal timing in daughters prenatally exposed to antibiotics at any point in pregnancy was -0.1 (95 % CI: -0.9; 0.7) months compared to unexposed daughters. Both the trimester-specific analyses and the active comparator analysis revealed similar results.

CONCLUSION

Prenatal exposure to antibiotics was not associated with pubertal timing.

In Utero Exposure to Glucocorticoids and Pubertal Timing in Sons and Daughters

Early pubertal timing has been associated with adult diseases, and identifying preventable causes is of importance. In utero exposure to exogenous glucocorticoids, has been associated with changes in the reproductive hormonal axes in the children, which may influence pubertal timing. Exogenous glucocorticoids can be indicated for diseases such as asthma, allergy, skin diseases, as well as muscle and joint diseases. The aim was to explore the association between in utero exposure to glucocorticoids and pubertal timing in the children. This population-based study was conducted in the Puberty Cohort including 15,819 children, which is a sub-cohort of the Danish National Birth Cohort. Information on maternal glucocorticoid treatment was collected through interviews during pregnancy. Information on pubertal timing was obtained by questionnaires every 6 months throughout puberty, including Tanner Stages, axillary hair, acne, voice break, first ejaculation and menarche. The potential impact of confounding by indication was explored by stratifying on indication and treatment status. Overall, 6.8% of the children were exposed to glucocorticoids in utero. Exposure to glucocorticoids in utero was not associated with earlier puberty for neither boys nor girls with combined estimates of 0.4 months (95% CI: -1.5; 2.2) and -0.7 months (95% CI: -2.5; 1.2).

Alcohol intake during pregnancy and timing of puberty in sons and daughters: A nationwide cohort study

We explored whether maternal alcohol intake in early pregnancy is associated with pubertal timing in sons and daughters. In total, 15,819 children, born 2000-2003 within the Danish National Birth Cohort, gave half-yearly, self-reported information on pubertal development (Tanner stages, voice break, first ejaculation, menarche, acne, and axillary hair) from 11 years during 2012-2018. Information on maternal average alcohol intake in first trimester and binge drinking episodes (intake of ≥5 drinks on the same occasion) in first trimester was self-reported by mothers during pregnancy. Average alcohol intake of 5+ weekly drinks in first trimester was not associated with pubertal timing in sons (with no alcohol intake as the reference). A tendency towards earlier pubertal timing was observed in daughters (-2.0 (95 % confidence interval: -4.2, 0.3) months) when combining the estimates for all pubertal milestones. Binge drinking was not associated with pubertal timing in neither sons nor daughters.

Size at birth, infant growth, and age at pubertal development in boys and girls

Purpose

This study investigated whether size at birth and infant growth were associated with age of indicators of pubertal development in boys and girls. We hypothesized that restricted fetal growth and accelerated infant growth lead to earlier pubertal age.

Patients and methods

In total, 15,822 boys and girls answered questionnaires half-yearly with information on pubertal development: age at menarche, first ejaculation, voice break, Tanner stages, axillary hair, and acne. Birth weight and gestational age were used to calculate birth weight Z-scores. Changes in infant weight Z-score from 0 to 5, 5 to 12, and 0 to 12 months were estimated. We estimated the mean monthly difference in timing of puberty between children born small-for-gestational age (SGA) and large-for-gestational age (LGA) with children born appropriate-for-gestational age (AGA) as reference. We further investigated whether increasing infant weight Z-scores were associated with age at attaining indicators of pubertal development.

Results

Girls born SGA reached all pubertal markers at an earlier mean age than girls born AGA, as indicated by mean age differences below zero (eg, age at menarche: -2.3 months, 95% CI: -3.4, -1.2), except for breast development. Girls born LGA reached pubertal markers later than girls born AGA (eg, age at menarche: 1.7 months, 95% CI 0.5, 2.9). Boys born SGA and LGA achieved puberty earlier than boys born AGA, though with CIs crossing zero (eg, age at voice break for SGA: -0.7 months, 95% CI -2.1, 0.7 and for LGA: -0.7 months, 95% CI -2.1, 0.8). A 1-unit increase in weight Z-score from 0 to 12 months was associated with a mean age difference of -1.7 to -0.3 months for pubertal development in both sexes.

Conclusion

Small size at birth and rapid infant growth were associated with early pubertal age, most consistent and pronounced in girls.

Maternal pre-pregnancy body mass index, smoking in pregnancy, and alcohol intake in pregnancy in relation to pubertal timing in the children

Background

Earlier pubertal timing has been observed in many countries. We aimed to explore if prenatal exposure to maternal obesity, smoking, and alcohol intake was associated with timing of puberty by use of a novel marker of pubertal timing: ‘the height difference in standard deviations’ (HD:SDS).

Methods

HD:SDS is the difference between pubertal height in standard deviations and adult height in standard deviations, and it correlates well with age at peak height velocity. Pubertal height was measured by health care professionals at approximately 13 years in boys and 11 years in girls, and the children’s adult height was predicted from parental height reported by the mothers during pregnancy. Information on HD:SDS was available for 42,849 of 56,641 eligible boys and girls from the Danish National Birth Cohort born 2000–2003. In a subsample, HD:SDS was validated against age at the following self-reported pubertal milestones: Tanner stages, menarche, first ejaculation, voice break, acne, and axillary hair. Prenatal exposures were reported by mothers during pregnancy.

Results

HD:SDS correlated moderately with the pubertal milestones considered (correlation coefficients: − 0.20 to − 0.53). With normal weight (body mass index (BMI): 18.5–24.9 kg/m²) as the reference, maternal pre-pregnancy obesity (BMI: 30.0+ kg/m²) was associated with earlier pubertal timing: 0.23 (95% confidence interval (CI): 0.18, 0.28) higher HD:SDS in boys and 0.19 (95% CI, 0.14, 0.24) higher HD:SDS in girls. Maternal smoking was not associated with pubertal timing. Compared to alcohol abstainers, maternal intake of > 3 units of alcohol weekly was associated with later puberty in boys only: 0.14 (95% CI, 0.05, 0.24) lower HD:SDS.

Conclusion

As correlations between HD:SDS and the considered pubertal milestones were comparable to those reported in the literature between age a peak height velocity and the considered pubertal milestones, the validity of HD:SDS seems acceptable. Maternal pre-pregnancy obesity was associated with earlier pubertal timing in both sexes, and maternal alcohol intake during pregnancy was associated with later pubertal timing in boys. Maternal smoking has been linked to earlier timing of puberty, but this was not replicated in our setting using HD:SDS as a marker of pubertal timing.

Pubertal development after unintended intrauterine exposure to oral contraceptives: a nationwide cohort study

OBJECTIVE

To study the associations between exposure to oral contraceptives before conception and early in pregnancy and pubertal timing in boys and girls.

DESIGN

Population-based cohort study.

SETTING

Not applicable.

PATIENT(S)

Overall, 15,800 children (70%) born during 2000-2003 into the Danish National Birth Cohort were categorized according to maternal use of combined oral contraceptive pills or progestin-only pills reported around gestational week 17: no exposure (reference), exposure 4 months before conception, and exposure in early pregnancy. Children self-assessed pubertal status using Web-based questionnaires from 11 years and biannually throughout puberty.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Adjusted mean age differences (months) for attaining individual pubertal milestones and overall pubertal timing. Proportion mediated by prepubertal body mass index.

RESULT(S)

In boys, intrauterine exposure to oral contraceptives showed a tendency toward slightly earlier mean age for voice break (months, -3.8; 95% confidence interval [CI] -6.5, -1.0) and first ejaculation (months, -2.9; 95% CI -5.9, 0.1) and a mean difference of -1.4 months (95% CI -3.3, 0.4) for overall pubertal timing. Girls with intrauterine exposure tended to have slightly earlier age at menarche (months, -1.9; 95% CI -4.0, 0.3) and Tanner breast stages and had a mean difference of -0.9 months (95% CI -2.7, 1.0) for overall pubertal timing. Exposure before conception was not associated with pubertal timing. Prepubertal body mass index did not play a mediating role.

CONCLUSION(S)

This study shows some evidence that intrauterine exposure to oral contraceptives might slightly affect pubertal timing.