Lessons from large population studies on timing and tempo of puberty (secular trends and relation to body size): the European trend

Association between body fat distribution and age at menarche: a two sample Mendelian randomization study

Background

Numerous studies have examined the association between obesity and age at menarche (AAM), with most focusing on traditional obesity indicators such as body mass index. However, there are limited studies that explored the connection between body fat distribution and AAM, as well as a scarcity of Mendelian randomization (MR) studies.

Methods

In this study, we conducted a two-sample MR study to evaluate the causal effects of eight body fat distribution indicators on AAM. Inverse variance weighted (IVW) method was used for primary analysis, while supplementary approaches such as MR-Egger and weighted median were also utilized. Considering that the eight exposures were highly correlated, we performed an MR Bayesian model averaging (MR-BMA) analysis to prioritize the effect of major exposure on AAM. A series of sensitivity analyses were also performed.

Results

From a range of 82-105 single nucleotide polymorphisms (SNPs) were utilized as genetic instrumental variables for each of the exposure factors. After Bonferroni correction, we found that whole body fat mass (β: -0.17; 95% CI: -0.24, -0.11), left leg fat percentage (β: -0.14; 95% CI: -0.21, -0.07), left leg fat mass (β: -0.20; 95% CI: -0.27, -0.12), left arm fat percentage (β: -0.18; 95% CI: -0.26, -0.11) and left arm fat mass (β: -0.18; 95%CI: -0.26, -0.10) were associated with decreased AAM using random effects IVW method. And the beta coefficients for all MR evaluation methods exhibited consistent trends. MR-BMA method validated that left arm fat percentage plays a dominant role in AAM.

Conclusions

Our MR study suggested that body fat has broad impacts on AAM. Obtaining more information on body measurements would greatly enhance our comprehension of pubertal development.

Annual Research Review: Sex, gender, and internalizing conditions among adolescents in the 21st century - trends, causes, consequences

Internalizing conditions of psychopathology include depressive and anxiety disorders; they most often onset in adolescence, are relatively common, and contribute to significant population morbidity and mortality. In this research review, we present the evidence that internalizing conditions, including depression and anxiety, as well as psychological distress, suicidal thoughts and self-harm, and fatal suicide, are considerably increasing in adolescent populations across many countries. Evidence indicates that increases are currently greatest in female adolescents. We present an epidemiological framework for evaluating the causes of these increases, and synthesize research on whether several established risk factors (e.g., age of pubertal transition and stressful life events) and novel risk factors (e.g., digital technology and social media) meet conditions necessary to be plausible causes of increases in adolescent internalizing conditions. We conclude that there are a multitude of potential causes of increases in adolescent internalizing conditions, outline evidence gaps including the lack of research on nonbinary and gender nonconforming populations, and recommend necessary prevention and intervention foci from a clinical and public health perspective.

Reproductive risk factors across the female lifecourse and later metabolic health

Metabolic health is characterized by optimal blood glucose, lipids, cholesterol, blood pressure, and adiposity. Alterations in these characteristics may lead to the development of type 2 diabetes mellitus or dyslipidemia. Recent evidence suggests that female reproductive characteristics may be overlooked as risk factors that contribute to later metabolic dysfunction. These reproductive traits include the age at menarche, menstrual irregularity, the development of polycystic ovary syndrome, gestational weight change, gestational dysglycemia and dyslipidemia, and the severity and timing of menopausal symptoms. These risk factors may themselves be markers of future dysfunction or may be explained by shared underlying etiologies that promote long-term disease development. Disentangling underlying relationships and identifying potentially modifiable characteristics have an important bearing on therapeutic lifestyle modifications that could ease long-term metabolic burden. Further research that better characterizes associations between reproductive characteristics and metabolic health, clarifies underlying etiologies, and identifies indicators for clinical application is warranted in the prevention and management of metabolic dysfunction.

Trends in age at menarche from 1943 through 1989 in Taiwan: A retrospective population-based analysis

BACKGROUND

Recent studies have demonstrated a global decline in the age at menarche. Our study aimed to determine the age at menarche of Taiwanese women born between 1943 and 1989.

METHODS

Data were obtained from the Taiwan Biobank. To view the trends in age at menarche, we analyzed data from 74,799 women. The mean, standard deviation, and annual percentage change in age at menarche were calculated for birth-year cohorts.

RESULTS

The mean age at menarche of Taiwanese women born in 1943 was 14.85 years. The age at menarche decreased to 12.20 years for those born in 1989. The mean age at menarche declined by 2.65 years across the 47-year study period; hence, the reduction rate was 0.56 years per decade. This study demonstrated a downward secular trend in the age at menarche of Taiwanese women born between 1943 and 1989. This trend occurred in three stages of decline: fast (1943-1953), slow (1953-1965), and moderate (1965-1989).

CONCLUSION

The age at menarche decreased by 2.65 years among Taiwanese women born in 1943 compared with those born in 1989. This decline occurred in three stages: fast (1943-1953), slow (1953-1965), and moderate (1965-1989). This significant downward secular trend in age at menarche reflects Taiwan's socioeconomic development.

Secular trends in skill-related physical fitness among Slovenian children and adolescents from 1983 to 2014

It is vital from the public health and educational perspective to be familiar with changes in the fitness levels of individuals and populations since fitness is associated with several health outcomes and cognition. Skill-related physical fitness refers to performance in sports or occupation and is associated with motor skill performance. The aim of the present study was to examine secular trends in skill-related physical fitness of 16 678 participants in four youth generations of Slovenian children and adolescents in years 1983 (n = 3128), 1993/94 (n = 3413), 2003/04 (n = 5497), and 2013/14 (n = 4640). Using repeated cross-sectional design, we observed fitness level of all participants divided into three age groups: 6-10, 11-14, and 15-19 years. Skill-related physical performance was measured with seven fitness tests for speed, coordination, balance, and flexibility. Analysis of covariance was used to compare differences in fitness performance between decades in each age and sex group, adjusted for body height, body weight, and body mass index. Overall, large but inconsistent changes in coordination, a small improvement in speed, and a decline in flexibility were seen. The trends over the whole examined period were not linear throughout decades. Generally, positive trends were noticed in periods 1983-1993 (range 1.4%-17.9%; except flexibility) and 2003/04-2013/14 (range 0.2%-36.4%; except age group 15-19 years) while in the period 1993/94-2003/04 there are some particularities in secular trends according to individual components as well as age groups. In general, the secular trend showed a positive direction for both genders (p < 0.05), except for gross motor coordination, which demonstrated positive trends in 1993 and 2013 compared with a decade earlier (p < 0.05) and from 1983 to 2013/14, except for the youngest boys in 2003 and the youngest girls from 1993 to 2003 (p < 0.05). Our findings call for exercise programs aimed at improving speed and gross motor coordination in both sexes and all age groups, especially in the group of 15-19 years old.

Prenatal exposure to nitrosatable drugs and timing of puberty in sons and daughters: A nationwide cohort study

BACKGROUND

N-nitroso compounds (NOCs) can be formed by endogenous reactions between nitrosatable drugs and nitrite. Animal studies have found that several NOCs are teratogenic, and epidemiological studies report associations between prenatal exposure to nitrosatable drugs and adverse birth outcomes. It is unknown whether prenatal exposure to nitrosatable drugs is harmful to the child's reproductive health, including pubertal development.

OBJECTIVES

We investigated whether prenatal exposure to nitrosatable drugs was associated with timing of puberty and whether nitrate, nitrite and antioxidant intake modified any association.

METHODS

The population-based Danish National Birth Cohort (DNBC) Puberty Cohort, which includes 15,819 children, was used to investigate the association between prenatal exposure to nitrosatable drugs and timing of puberty. Around gestational week 11 and gestational week 18, mothers provided information about drug use during pregnancy. The children's self-reported information on onset of pubertal milestones was collected every six months from 11 years of age and throughout puberty. To investigate potential effect modification by nitrite, nitrate and antioxidant intake, information on these factors was obtained from a food frequency questionnaire completed by the mothers in gestational week 25, and information on nitrate concentration in maternal drinking water at her residential address was obtained from monitoring data from public waterworks. Data were analysed using a multivariable regression model for interval-censored data estimating difference in months in timing of puberty between exposure groups.

RESULTS

A total of 2,715 children were prenatally exposed to nitrosatable drugs. We did not find an association between prenatal exposure to nitrosatable drugs and timing of puberty. This finding was supported by null-findings in the following sub-analyses investigating: 1. subtypes of nitrosatable drugs (secondary and tertiary amines and amides), 2. dose-dependency (duration of drug intake), 3. effect modification by maternal intake of nitrate, nitrite, and antioxidants. 4. confounding by indication.

CONCLUSIONS

Prenatal exposure to nitrosatable drugs was not associated with timing of puberty. Nitrosatable drugs are commonly used drugs in pregnancy, and further research is needed to allow firm conclusions on the potential effect of prenatal exposure to nitrosatable drugs on the child's reproductive health.

Maternal intake of folate and folic acid during pregnancy and pubertal timing in girls and boys: A population-based cohort study

BACKGROUND

Folate is essential for normal foetal development as it plays an important role for gene expression during different periods of foetal development. Thus, prenatal exposure to folate may have a programming effect on pubertal timing.

OBJECTIVES

To study the association between maternal intake of folate during pregnancy and pubertal timing in girls and boys.

METHODS

We studied 6585 girls and 6326 boys from a Danish population-based Puberty Cohort, 2000-2021. Information on maternal intake of folate from diet and folic acid from supplements was obtained from a food-frequency questionnaire in mid-pregnancy, and total folate was calculated as dietary folate equivalents. Information on age at menarche in girls, age at first ejaculation and voice break in boys, and Tanner stages, acne and axillary hair in both girls and boys was obtained every 6 months throughout puberty. We estimated mean monthly differences according to exposure groups for each pubertal milestone in addition to a combined estimate for the average age at attaining all pubertal milestones using multivariable interval-censored regression models. Total folate was analysed in quintiles, continuous and as restricted cubic splines.

RESULTS

Maternal intake of total folate in mid-pregnancy was not associated with pubertal timing in girls (combined estimate for overall pubertal timing per standard deviation (SD 325 μg/day) decrease in maternal intake of total folate: -0.14 months (95% confidence interval [CI] -0.51, 0.22)). Boys had slightly later overall pubertal timing per standard deviation (SD 325 μg/day) decrease in maternal intake of total folate (combined estimate: 0.40 months, 95% CI 0.01, 0.72). Spline plots supported these findings.

CONCLUSIONS

Prenatal exposure to low maternal intake of total folate in mid-pregnancy was not associated with pubertal timing in girls but associated with slightly later pubertal timing in boys. This minor delay is likely not of clinical importance.

PFAS and Phthalate/DINCH Exposure in Association with Age at Menarche in Teenagers of the HBM4EU Aligned Studies

Early puberty has been found to be associated with adverse health outcomes such as metabolic and cardiovascular diseases and hormone-dependent cancers. The decrease in age at menarche observed during the past decades has been linked to an increased exposure to endocrine-disrupting compounds (EDCs). Evidence for the association between PFAS and phthalate exposure and menarche onset, however, is inconsistent. We studied the association between PFAS and phthalate/DINCH exposure and age at menarche using data of 514 teenagers (12 to 18 years) from four aligned studies of the Human Biomonitoring for Europe initiative (HBM4EU): Riksmaten Adolescents 2016-2017 (Sweden), PCB cohort (follow-up; Slovakia), GerES V-sub (Germany), and FLEHS IV (Belgium). PFAS concentrations were measured in blood, and phthalate/DINCH concentrations in urine. We assessed the role of each individual pollutant within the context of the others, by using different multi-pollutant approaches, adjusting for age, age- and sex-standardized body mass index z-score and household educational level. Exposure to di(2-ethylhexyl) phthalate (DEHP), especially mono(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), was associated with an earlier age at menarche, with estimates per interquartile fold change in 5OH-MEHP ranging from -0.34 to -0.12 years in the different models. Findings from this study indicated associations between age at menarche and some specific EDCs at concentrations detected in the general European population, but due to the study design (menarche onset preceded the chemical measurements), caution is needed in the interpretation of causality.

Endocrine Health and Health Care Disparities in the Pediatric and Sexual and Gender Minority Populations: An Endocrine Society Scientific Statement

Endocrine care of pediatric and adult patients continues to be plagued by health and health care disparities that are perpetuated by the basic structures of our health systems and research modalities, as well as policies that impact access to care and social determinants of health. This scientific statement expands the Society's 2012 statement by focusing on endocrine disease disparities in the pediatric population and sexual and gender minority populations. These include pediatric and adult lesbian, gay, bisexual, transgender, queer, intersex, and asexual (LGBTQIA) persons. The writing group focused on highly prevalent conditions-growth disorders, puberty, metabolic bone disease, type 1 (T1D) and type 2 (T2D) diabetes mellitus, prediabetes, and obesity. Several important findings emerged. Compared with females and non-White children, non-Hispanic White males are more likely to come to medical attention for short stature. Racially and ethnically diverse populations and males are underrepresented in studies of pubertal development and attainment of peak bone mass, with current norms based on European populations. Like adults, racial and ethnic minority youth suffer a higher burden of disease from obesity, T1D and T2D, and have less access to diabetes treatment technologies and bariatric surgery. LGBTQIA youth and adults also face discrimination and multiple barriers to endocrine care due to pathologizing sexual orientation and gender identity, lack of culturally competent care providers, and policies. Multilevel interventions to address these disparities are required. Inclusion of racial, ethnic, and LGBTQIA populations in longitudinal life course studies is needed to assess growth, puberty, and attainment of peak bone mass. Growth and development charts may need to be adapted to non-European populations. In addition, extension of these studies will be required to understand the clinical and physiologic consequences of interventions to address abnormal development in these populations. Health policies should be recrafted to remove barriers in care for children with obesity and/or diabetes and for LGBTQIA children and adults to facilitate comprehensive access to care, therapeutics, and technological advances. Public health interventions encompassing collection of accurate demographic and social needs data, including the intersection of social determinants of health with health outcomes, and enactment of population health level interventions will be essential tools.

Genetic prediction of age at menarche, age at natural menopause and type 2 diabetes: A Mendelian randomization study

BACKGROUND AND AIMS

The relationship between reproductive factors and type 2 diabetes (T2D) is controversial; therefore, we explored the causal relationship of age at menarche (AAM), age at natural menopause (ANM), with the risk of T2D and glycemic traits using two-sample Mendelian randomization.

METHODS AND RESULTS

We used publicly available data at the summary level of genome-wide association studies, where AAM (N = 329,345), ANM (N = 69,360), T2D (N = 464,389). The inverse variance weighting (IVW) method was employed as the primary method. To demonstrate the robustness of the results, we also conducted various sensitivity analysis methods including the MR-Egger regression, the weighted median (WM) and the MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test. After excluding IVs associated with confounders, we found a causal association between later AAM and reduced risk of T2D (OR 0.81 [95% CI 0.75, 0.87]; P = 2.20 × 10^-8), lower levels of FI (β -0.04 [95% CI -0.06, -0.01]; P = 2.19 × 10^-3), FPG (β -0.03 [95% CI -0.05, -0.007]; P = 9.67 × 10^-5) and HOMA-IR (β -0.04 [95% CI -0.06, -0.01]; P = 4,95 × 10^-3). As for ANM, we only found a causal effect with HOMA-IR (β -0.01 [95% CI -0.02, -0.005]; P = 1.77 × 10^-3), but not with T2D.

CONCLUSIONS

Our MR study showed a causal relationship between later AAM and lower risk of developing T2D, lower FI, FPG and HOMA-IR levels. This may provide new insights into the prevention of T2D in women.

Secular trends in motor performance in Swiss children and adolescents from 1983 to 2018

Introduction

Environmental changes, including globalization, urbanization, social and cultural changes in society, and exposure to modern digital technology undoubtedly have an impact on children’s activity and lifestyle behavior. In fact, marked reductions in children’s physical activity levels have been reported over the years and sedentary behavior has increased around the world. The question arises whether these environmental changes had an impact on general motor performance in children and adolescents. The study aimed to investigate secular trends of motor performance in Swiss children and adolescents, aged between 7 and 18 years, over a period of 35 years from 1983 to 2018.

Methods

Longitudinal data on the five motor components of the Zurich Neuromotor Assessment (ZNA) – pure motor (PM), fine motor (FM), dynamic balance (DB), static balance (SB), and contralateral associated movements (CAM) – were pooled with cross-sectional data on PM and FM from eight ZNA studies between 1983 and 2018. Regression models were used to estimate the effect of the year of birth on motor performance and body mass index (BMI) measurements. Models were adjusted for age, sex, and socioeconomic status.

Results

The secular trend estimates in standard deviation scores (SDS) per 10 years were − 0.06 [−0.33; 0.22, 95% Confidence Interval] for PM, −0.11 [−0.41; 0.20] for FM, −0.38 [−0.66; −0.09] for DB (−0.42 when controlled for BMI), −0.21 [−0.47; 0.06] for SB, and − 0.01 [−0.32; 0.31] for CAM. The mean change in BMI data was positive with 0.30 SDS [0.07; 0.53] over 10 years.

Discussion

Despite substantial societal changes since the 1980s, motor performance has remained relatively stable across generations. No secular trend was found in FM, PM, SB, and CAM over a period of 35 years. A secular trend in DB was present independent of the secular trend in body mass index.

Early physical maturation and subjective health complaints in adolescent girls: a pooled cross-sectional analysis

BACKGROUND

Although adolescents are generally healthy, subjective health complaints (SHC) are common in this age group, especially in adolescent girls. We explored the association between early menarche and the frequency of psychosomatic symptoms and how this association varies between countries.

METHODS

Our sample included 298 000 adolescent girls from 2002, 2006, 2010 and 2014 cycles of the Health Behaviour in School-aged Children (HBSC) study in 41 European and North American countries. School surveys measured the frequency of eight psychosomatic symptoms in the past 6 months. Early maturation was defined as self-reported age at menarche below 11 years. Using logistic regression, we estimated adjusted ORs (aORs) and 95% CIsof experiencing each psychosomatic symptom at least more than once a week and experiencing two or more symptoms at least more than once a week.

RESULTS

Early menarche occurred in 4.73% of the sample and was positively related to headache, stomachache, backache, feeling low, irritability or bad temper, feeling nervous, difficulties in sleeping, feeling dizzy and two or more of these symptoms, respectively (all p values<0.001). The interactions between early menarche and survey circle were non-significant. Changing the age criterion to 12 years did not affect the results. The associations between early menarche and psychosomatic symptoms were robust across the HBSC-participating counties with two age criteria.

CONCLUSIONS

Early menarche positively relates to various psychosomatic symptoms in European and North American adolescent girls. Our findings suggest that early-maturing girls may need early supportive interventions.

Causal relationships between birth weight, childhood obesity and age at menarche: A two-sample Mendelian randomization analysis

OBJECTIVES

Observational studies suggest birth weight and childhood obesity are closely associated with age at menarche. However, the relationships between them are currently inconsistent and it remains elusive whether such associations are causal. Therefore, the aim of the study was to investigate whether there existed causal relationships between birth weight, childhood obesity and age at menarche.

DESIGN, PATIENTS AND MEASUREMENTS

A two-sample Mendelian randomization (MR) study. The standard inverse variance weighted MR analyses were adopted to evaluate the causal effects of birth weight (n = 143,677), childhood body mass index (BMI) (n = 39,620) on age at menarche (n = 182,416) with summary statistics from large-scale genome-wide association studies (GWASs). Meanwhile, we validated our MR results with some sensitivity analyses including maximum likelihood, weighted-median and MR pleiotropy residual sum and outlier methods.

RESULTS

The present study showed that each one standard deviation (1-SD) lower birth weight was predicted to result in a 0.1479 years earlier of age at menarche (β = .1479, 95% confidence interval [CI] = 0.0422-0.2535; p = 0.0061). We also found that genetically predicted 1-SD increase in childhood BMI was causally associated with early age at menarche (β = -.3966, 95% CI = -0.5294 to -0.2639; p = 4.73E-09).

CONCLUSIONS

Our MR study suggests the causal effect of lower birth weight and higher childhood BMI on the increased risk of earlier menarche. It may be the opportune time to carry out weight control intervention in prenatal and early childhood development periods to prevent early menarche onset, thus decreasing the future adverse consequences.

Maternal age at menarche and reproductive health in young adult men: a cohort study

STUDY QUESTION

Is maternal age at menarche associated with reproductive health in sons measured by semen quality, testes volume and reproductive hormone levels?

SUMMARY ANSWER

Later maternal age at menarche was associated with impaired semen characteristics, lower testes volume and altered levels of reproductive hormones, while earlier maternal age at menarche was not strongly associated with reproductive outcomes in sons.

WHAT IS KNOWN ALREADY

Both earlier and later maternal age at menarche may be associated with altered male reproductive health outcomes. This is the first study to investigate the potential association between maternal age at menarche and semen quality, testes volume and reproductive hormone levels in sons.

STUDY DESIGN, SIZE, DURATION

In this population-based cohort study, we used data from the Fetal Programming of Semen Quality Cohort nested within the Danish National Birth Cohort. In total, 5697 sons born in 1998-2000 were invited to participate in the cohort in 2017-2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 1043 (18% of the invited) young men with information on maternal age at menarche provided a semen and blood sample, measured their testes volume, and filled in a questionnaire on health behavior and pubertal development. Maternal age at menarche was reported by the mothers during pregnancy and examined categorically (as earlier, at the same time or later than their peers), continuously and modeled as splines. We estimated relative percentage differences in the reproductive outcomes using negative binomial regression models. Further, we did a mediation analysis to investigate the potential mediating role of timing of the sons' pubertal development.

MAIN RESULTS AND THE ROLE OF CHANCE

Sons whose mothers had age at menarche later than peers had 15% lower (95% CI: -27%; 0%) sperm concentration, 14% lower (95% CI: -28%; 1%) total sperm count, 7% higher (95% CI: 0%; 14%) proportion of nonprogressive or immotile spermatozoa, 6% lower (95% CI: -11%; 0%) testes volume, 6% lower (95% CI: -12%; 1%) luteinizing hormone, 6% lower (95% CI: -12%; 1%) sex hormone-binding globulin and 5% lower (95% CI: -9%; 0%) testosterone levels compared with sons whose mothers had age at menarche at the same time as peers. Our study did not suggest that earlier maternal age at menarche was strongly associated with semen quality, testes volume or reproductive hormones in sons. However, the spline analyses indicated a potential inverted U-shaped association for sperm concentration and testes volume, and levels of sex hormone-binding globulin and testosterone. We found no strong evidence of mediation by timing of the sons' own pubertal development.

LIMITATIONS, REASONS FOR CAUTION

There was a rather low participation rate in the Fetal Programming of Semen Quality Cohort and we tried to counter it by applying selection weights. Maternal age at menarche was recalled during pregnancy, which may introduce misclassification, most likely nondifferential. Inaccuracy of the sons' recalled pubertal development years after the event may result in underestimation of the possible mediating role of pubertal timing.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings may represent a degree of shared heritability of reproductive health or be a result of an underlying epigenetic profile or unknown shared environmental, cultural or dietary exposure, causing both altered age at menarche and impaired reproductive health outcomes in sons. However, the exact mechanism for the investigated association remains unknown.

STUDY FUNDING/COMPETING INTEREST(S)

This article is part of the ReproUnion collaborative study, cofinanced by the European Union, Intereg V ÖKS (20200407). The FEPOS project was further funded by the Lundbeck Foundation (R170-2014-855), the Capital Region of Denmark, Medical doctor Sofus Carl Emil Friis and spouse Olga Doris Friis's Grant, Axel Muusfeldt's Foundation (2016-491), A.P. Møller Foundation (16-37), the Health Foundation and Dagmar Marshall's Fond. Additionally, this study received funding from Aarhus University. There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Mechanism of leptin-NPY on the onset of puberty in male offspring rats after androgen intervention during pregnancy

OBJECTIVES

The time of onset of puberty has been increasingly earlier, but its mechanism is still unclear. This study aimed to reveal the mechanism of leptin and NPY in the onset of puberty in male offspring rats after androgen intervention during pregnancy.

METHODS

Eight-week-old specific pathogen-free (SPF) healthy male Sprague-Dawley (SD) rats and 16 female SD rats were selected and caged at 1:2. The pregnant rats were randomly divided into the olive oil control group (OOG) and testosterone intervention group (TG), with 8 rats in each group. Olive oil and testosterone were injected from the 15th day of pregnancy, for a total of 4 injections (15th, 17th, 19th, 21st day). After the onset of puberty, the male offspring rats were anesthetized with 2% pentobarbital sodium to collect blood by ventral aorta puncture and decapitated to peel off the hypothalamus and abdominal fat. Serum testosterone (T), free testosterone (FT), dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), sex hormone binding globulin (SHBG), and leptin were detected by ELISA, and then the free androgen index (FAI) was calculated. The mRNA levels of androgen receptor (AR), estrogen receptor α (ERα), NPY, leptinR, and NPY2R in the hypothalamus and abdominal fat were detected by RT-PCR. Protein expression levels of AR, ERα, NPY, leptinR, and NPY2R in the arcuate nucleus (ARC) of the hypothalamus were detected by immunohistochemistry.

RESULTS

The time of onset of puberty was significantly earlier in the TG than in the OOG (P< 0.05) and was positively correlated with body weight, body length, abdominal fat, and leptinR mRNA levels in adipose tissue in the OOG (P< 0.05), while it was positively correlated with serum DHT and DHEA concentrations and FAI and AR mRNA levels in the hypothalamus in the TG (P< 0.05). The NPY2R mRNA level and protein expression levels of ERα, NPY2R, and leptinR in the TG were significantly higher than those in the OOG, while the protein expression levels of AR and NPY in the TG were significantly lower than those in the OOG (P< 0.05).

CONCLUSIONS

Testosterone intervention during pregnancy led to an earlier onset of puberty in male offspring rats, which may render the male offspring rats more sensitive to androgens, leptin, and NPY at the onset of puberty.

Prenatal nitrate exposure from diet and drinking water and timing of puberty in sons and daughters: A nationwide cohort study

BACKGROUND

In Western countries, age at pubertal development has declined during the last century in girls, and probably also in boys. No studies have investigated whether nitrate, a widespread environmental exposure with teratogenic and hormone disrupting properties, might affect timing of puberty.

OBJECTIVES

We investigated if prenatal exposure to nitrate from drinking water and diet was associated with timing of puberty.

METHODS

This cohort study included 15,819 children born from 2000 to 2003 within the Danish National Birth Cohort. Self-reported information on current status of various pubertal milestones was provided every six months by a questionnaire from 11 years of age until 18 years or full maturity, whichever came first. Maternal nitrate intake from diet (mg/day) was derived from a mid-pregnancy food frequency questionnaire and individual level nitrate exposure from drinking water (mg/L) was derived using measurements from Danish public waterworks. Adjusted average differences in months in age at attaining several pubertal milestones as well as the average age difference in age at attaining all the milestones were estimated separately for diet and water using a regression model for interval-censored data. C- and E-vitamin, red meat and processed meat intake were explored as potential effect modifiers in sub-analyses.

RESULTS

No strong associations were observed between prenatal exposure to nitrate and timing of puberty in children. However, sons born of mothers with a nitrate concentration in drinking water at their residential address of > 25 mg/L (half of the World Health Organisation (WHO) guideline value) compared with ≤ 1 mg/L showed a tendency towards earlier age at pubertal development with an average age difference of -1.2 months (95 % confidence interval,-3.0;0.6) for all the pubertal milestones combined.

DISCUSSION

Studies including more highly exposed children are needed before the current WHO drinking water guideline value for nitrate can be considered safe concerning pubertal development.

The relationship between social determinants of health and girls’ age at menarche based on the world health organization model: path analysis

Objectives

Given the descending trend of menarche age and the effect of social determinants of health on menarche, the present study was conducted to examine the relationship model of social determinants of health with menarche age of girls.

Materials and methods

The present cross-sectional study enrolled 840 mothers and their 6-17 year-old daughters in the city of Kashan, Iran (2020). Questionnaires used included: demographic-family questionnaire for mothers and daughters, question about age at menarche, Perceived Social Support, Physical Activity, Socioeconomic Status, Spiritual Health, General Health Questionnaire, the quality of couple's relationship and the family communication pattern. The statistical analysis was performed in SPSS-16, and the relationship model was examined using path analysis method in LISREL-8.8.

Results

The girls' menarche age was directly affected by sister's (b = 0.83) and mother's menarche age (b = 0.05), BMI (b = 0.01), physical activity (b = -0.06), conversation orientation (b = -0.002), socioeconomic status (b = -0.01) and maternal general health (b = 0.009). It was also indirectly affected by mother's menarche age, social support, socioeconomic status, and maternal spiritual health and parents relationships.

Conclusions

The results showed that the numerous factors affect the girls’ age at menarche directly and indirectly. Considering mutual interaction of factors revealed in the proposed model, it is recommended this model be used as an appropriate framework in research, design and implementation of programs relating to adolescent girls.

Maternal pre-pregnancy body mass index, gestational weight gain, and pubertal timing in daughters: A systematic review and meta-analysis of cohort studies

The timing of daughter's puberty onset is constantly earlier. It is still unclear about the maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) as important prenatal factors that may affect offspring's onset of puberty. Thus, we evaluated the association among maternal pre-pregnancy BMI, GWG, and daughters' early pubertal development based on the existing literature. Literature review was conducted in different databases, including Web of Science, Pubmed, Wiley, ScienceDirect, Web of Science, and Chinese National Knowledge Infrastructure databases up to June 2021. We selected random effects model or fixed effects model for meta-analysis according to the I² statistics value to obtain the summary measurement. A total of 12 cohort studies were included. Compared to maternal pre-pregnancy normal weight, maternal pre-pregnancy overall overweight/obesity (RR = 1.24; 95% CI 1.17 to 1.32), obesity (RR = 1.35; 95% CI 1.23 to 1.48), and overweight (RR = 1.17; 95% CI 1.09 to 1.26) were significantly associated with the increased risk of earlier timing of pubertal onset in daughters. Daughters born of mothers with pre-pregnancy overall overweight/obesity, obesity, and overweight had earlier pubertal onset compared to those born of mothers with normal weight ([mean difference = -3.03, 95% CI: -3.97 to -2.10], [mean difference = -3.50, 95% CI: -5.38 to -1.62], and [mean difference = -2.89, 95% CI: -4.07 to -1.71], respectively). The effects were also significant in the assessed three milestones (menarche, breast development, and pubic hair development). Maternal excessive GWG increased the risk of early pubertal timing in daughters (RR = 1.19; 95% CI 1.09 to 1.30).

Secular trends of age at menarche and the effect of famine exposure on age at menarche in rural Chinese women

BACKGROUND

Over the past few decades, more studies have suggested that the age at menarche (AAM) has continued to decline. However, the AAM for women in resource-constrained areas is not clear. Moreover, the association between the China famine and AAM is still unclear in rural regions.

AIM

The study aimed to investigate the secular trends of AAM for women born between 1935 and 2000 and to further explore the effect of famine on AAM in rural China.

SUBJECTS AND METHODS

The study included 23444 women participants from the baseline study of Henan Rural Cohort study. Changing AAM over time was analysed using linear regressions. Multinomial logistic regression was conducted to analyse the association between famine exposure and AAM subgroups.

RESULTS

The age-standardized mean AAM was 14.74 years. The average AAM declined from 16.98 years for those born in 1935 to 13.87 years for those born in 2000, a decline of 0.077 years per 1 year and 0.729 years per decade. Compared to the reference group, women exposed to famine during fetal, early childhood, middle childhood, and late childhood were 1.376 (95% CI, 1.071 - 1.769), 1.848(95% CI, 1.512 - 2.259), 2.084(95% CI, 1.725 - 2.518), and 2.146 (95% CI, 1.788 - 2.576) times more likely to be ≥18 years of AAM than unexposed famine women, respectively.

CONCLUSION

AAM showed a decreasing trend in rural China. Furthermore, both fetal and childhood famine exposure, especially in late childhood, were positively associated with increased AAM compared to unexposed famine.

Casual Associations and Shape Between Prepuberty Body Mass Index and Early Onset of Puberty: A Mendelian Randomization and Dose-Response Relationship Analysis

BACKGROUND

There is an ongoing controversial issue regarding whether onset of puberty is related to childhood BMI.

OBJECTIVES

This study aims at investigating the causal association and its shape between prepuberty BMI and early puberty onset.

METHODS

Breast development and testicular volume were assessed annually from a population-based prospective cohort of 997 children for consecutive years by professional endocrinologists. Seventeen puberty- and BMI-related SNPs were selected to calculate the polygenic risk score. The two-stage least square method was used to assess and confirm causal effects. A dose-response association between prepuberty BMI and early puberty onset was conducted by using restricted cubic spline Cox regression.

RESULTS

After adjusting for covariates, prepuberty BMI was positively associated with early thelarche among girls (coefficients = 0.18, 95% CI: 0.01, 0.29). A non-linear model suggested an inverted U-shaped relationship between prepuberty BMI and risk for early thelarche (χ² = 276.3, p < 0.001). The risk for early thelarche increased rapidly from prepuberty BMI at 15.70 kg/m² (P₂₅) to 20.75 kg/m² (P₈₅) and gradually decreased afterward. Compared with the P₂₅ of prepuberty BMI, the HRs (95% CI) for early thelarche were 5.08 (1.15, 8.55), 4.48 (1.02, 7.74), 10.15 (3.93, 17.50), and 8.43 (1.91, 13.71) for percentiles P₂₅-P₅₀, P₅₀-P₇₅, P₇₅-P₈₅, and ≥P₈₅ of BMI categories, respectively. In boys, compared with the P₂₅ of prepuberty BMI, boys with BMI between P₂₅ and P₅₀ showed an increased risk of early puberty (HR: 3.94, 95% CI: 1.44, 6.80).

CONCLUSIONS

Prepuberty BMI may serve the purpose of identifying the girls at higher risk of early thelarche, which could assist in the adaptation of prevention and intervention strategies targeting childhood obesity. The findings emphasize a non-linear correlation between prepuberty BMI and early puberty onset.

Association of phthalates and early menarche in Korean adolescent girls from Korean National Environmental Health Survey (KoNEHS) 2015-2017

Background

Phthalates are one of renowned endocrine-disrupting chemicals, although inconsistent results are present around their effect on onset of menarche. Our hypothesis is that pre-pubertal exposure to phthalates is associated with acceleration of menarche.

Methods

We analyzed a total of 236 middle school (7th to 9th grade) girls from Korean National Environmental Health Survey 2015-2017. We used multiple linear regression to investigate impact of eight phthalate metabolites on age of menarche. We also conducted logistic regression to evaluate association between phthalate metabolite concentrations and early onset of menarche, adjusting for grade, maternal age of menarche and body mass index (BMI).

Results

In linear regression analysis, no significant association was found for any phthalate metabolites. In logistic regression analysis, however, odds ratios (ORs) of early menarche were significantly increased for mono-n-butyl phthalate (MnBP) and for sum of all phthalates. When compared to group with the lowest level, high concentration group for MnBP presented significantly increased odds of early menarche (OR: 2.09; 95% confidence interval [CI]: 1.03, 4.23) after adjusting for grade, maternal age of menarche and BMI. Furthermore, high concentrations of sum of all phthalates were associated with significant increase of OR of early menarche (OR: 2.22; 95% CI: 1.10, 4.49) after adjustment, compared to the lowest concentration group.

Conclusions

Results of our study suggest that exposure to phthalates around puberty may be associated with increased risk of early menarche.

A secular trend in age at menarche in Yunnan Province, China: a multiethnic population study of 1,275,000 women

Background

Age at menarche (AAM) has shown different trends in women from different ethnic and economic regions in recent decades. Data on AAM among multiethnic women living in developing areas are scarce.

Methods

Data on AAM from 1,275,000 women among 26 ethnicities in Yunnan Province, China, who were born from 1965 to 2001 were obtained from the National Free Preconception Health Examination Project from 2010 to 2018. The patterns of AAM trends were analysed according to ethnic group, area of residence, and socioeconomic status.

Results

The mean AAM was 13.7 ± 1.21 years (95% CI 13.697–13.701), with a decrease from 14.12 (±1.41) among women born before 1970 to 13.3 (±1.04) among those born after 2000. The decline was 0.36 years per 10-year birth cohort, and the plateau has not yet been reached in Yunnan. A secular trend of earlier AAM was observed in all 26 ethnic groups. The fastest rate of decline was observed for the Bai ethnicity (0.36 years per decade). Consistent declining trends in AAM appeared among extreme-, middling-, and nonpoverty economic patterns from 1965 to 2001, with reductions of 1.19, 1.44, and 1.5 years, respectively (P < 0.001). The peak reduction among middling poverty and extreme poverty occurred in the early 2000s (0.4 and 0.32 years). Multivariate analysis showed a significant difference in the declining trends in AAM along rural/urban lines (P < 0.001).

Conclusion

There was a secular trend towards a younger AAM during the twentieth century and early twenty-first century birth cohorts in the Yunnan population. Considering the difference in AAM trends due to ethnic and socioeconomic status in Yunnan, the health authority should utilize flexible adjusted health care strategies in different regions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11951-x.

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.

Physical activity behaviours in adolescence: current evidence and opportunities for intervention

Young people aged 10-24 years constitute 24% of the world's population; investing in their health could yield a triple benefit-eg, today, into adulthood, and for the next generation. However, in physical activity research, this life stage is poorly understood, with the evidence dominated by research in younger adolescents (aged 10-14 years), school settings, and high-income countries. Globally, 80% of adolescents are insufficiently active, and many adolescents engage in 2 h or more daily recreational screen time. In this Series paper, we present the most up-to-date global evidence on adolescent physical activity and discuss directions for identifying potential solutions to enhance physical activity in the adolescent population. Adolescent physical inactivity probably contributes to key global health problems, including cardiometabolic and mental health disorders, but the evidence is methodologically weak. Evidence-based solutions focus on three key components of the adolescent physical activity system: supportive schools, the social and digital environment, and multipurpose urban environments. Despite an increasing volume of research focused on adolescents, there are still important knowledge gaps, and efforts to improve adolescent physical activity surveillance, research, intervention implementation, and policy development are urgently needed.

The relationship between body weight and dietary habits with respect to the timing of puberty among saudi children and adolescents

Objective

The objective is to investigate the timing of pubertal onset as determined by the development of secondary sexual characteristics in relation to body weight and dietary patterns among Saudi females.

Methods

Children/adolescents visiting general and endocrinology pediatric clinics in King AbdulAziz University Hospital were invited to participate in this study. Female subjects between the ages of 5 and 20 years were included in this study, and those with syndromic disease, chronic comorbidities, endocrinopathies, organic causes of precocious puberty, positive family history of early pubertal onset, and under chronic medication were excluded from the study. Data were collected through clinical interviews with the consent of the legal guardians, and physical examinations were conducted.

Results

A.

total of 164 females were investigated. The mean age of thelarche, adrenarche, and menarche was 10, 11.3, and 12.2 years, respectively. We found a significant correlation between higher weight standard deviation and an earlier age of both thelarche and adrenarche. In addition, daily consumption of fast foods was significantly associated with an earlier menarchal age. Consumption of nonorganic poultry was linked to early thelarche.

Conclusion

Efforts should be directed to increase public and community awareness that fast food consumption, inorganic poultry, and higher body weight are important modifiable factors that lead to an earlier onset of female puberty across different parameters: breast development, adrenarche, and menstruation.

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.

Age at menarche among rural school youth in west-central Poland: variation with weight status and population growth

Studies of age at menarche in Poland have a long history and consistently show an urban-rural gradient. The objectives of the study were to to estimate the age at menarche among school girls resident in ten rural communities of the Greater Poland province in 2016 and to compare ages at menarche by weight status and by population growth. The sample included 1146 girls, 7–16 years of age, resident in ten rural communities. Menarcheal status was obtained via interview. Heights and weights were measured; the BMI was calculated. Based on the latter, the girls were classified as thin, normal weight and overweight (including the obese) relative to IOTF criteria. Population growth between 1986 and 2016 in each community was estimated from local records. Ages at menarche were estimated with the probit regression protocol (SPSS) using the logistic model with log 10 transformation for the total sample and for the subsamples by weight status and population growth. The median age at menarche for the total sample of rural girls was 13.25±0.20 years. Menarche was earlier among Overweight (13.06±0.32 years) compared to Normal Weight (13.25±0.37 years) and Thin (13.81±0.41 years), and among girls resident in communities with Major population growth (12.58±0.44 years) compared to Little/No growth (13.65±0.14 years). Results of the present survey were generally consistent with recent surveys of age at menarche among rural girls in Poland and among girls classified by weight status. Corresponding comparative data relating menarche to population growth are lacking.

The influence of socioeconomic status on menarcheal age among Chinese school-age girls in Tianjin, China

The association between socioeconomic status and the onset age of menarche is still not conclusive. This cross-sectional study was conducted among primary and middle school girls aged 7 to 16 years old in Tianjin, China, to explore the distribution of menarcheal age and its association with socioeconomic status. A self-designed structured questionnaire was completed by students and their parents to collect information on socioeconomic status (i.e., family income, parental education level, living residence), menarcheal status, and covariates (weight status of girls and their parents, sleeping hours per day, physical activity). Information on menarcheal status included whether or not menarche had occurred (Yes/No) and the exact age at menarche. Linear regression analysis was used to explore the association between socioeconomic status and menarcheal age before and after covariate adjustment. Among 1485 eligible girls with complete information, 445 had experienced menarche, with an overall menarche rate of 30%. The mean age at menarche was 12.9 years (95% confidence interval 12.8-13.0). Urban girls experienced menarche earlier than rural girls did (12.1 years vs. 13.5 years). Univariate analysis showed that urban residence and higher parental education were associated with earlier onset of menarche. After covariate adjustment, the significance still existed. However, after adjusting further for residence, the significant association with the parental education disappeared. Only urban residence was still significantly associated, even after further adjustment for parental education and family income, with adjusted regression coefficients (95% confidence interval) of - 1.087 (- 1.340,-0.834), indicating that the onset age of menarche among urban girls was 1.087 years (0.834, 1.340) younger than that among rural girls. Family income was not related to the onset age of menarche in any analyses.Conclusion: Urban-rural differences played a more important role in the early onset of menarche than socioeconomic differences between families. What is Known: • The age at menarche varies by race and country, but the global trend is towards earlier onset as a result of changes in nutrition, family structure, socioeconomic status, and physical condition. What is New: • Urban girls experienced menarche earlier than rural girls, but this urban-rural difference could not be explained by family income, parental education, weight status of the participants and their parents, participants' physical exercise and sleeping hours. • Higher parental education was associated with earlier onset of menarche, but this association disappeared after adjustment for living residence.

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.

Low BMI, but not high BMI, influences the timing of puberty in boys

BACKGROUND

Previous studies investigating the association between weight status and onset of puberty in boys have been equivocal. It is currently unclear to what extent weight class influences puberty onset and progression.

OBJECTIVES

To explore the relationship between degree of sexual maturation and anthropometric measures in Norwegian boys.

METHODS

The following endpoints were collected in a Norwegian cross-sectional study of 324 healthy boys aged 9-16: ultrasound-determined testicular volume (USTV), total serum testosterone, Tanner pubic hair stage, height, weight, waist circumference (WC), subscapular skinfolds (SSF), and body fat percentage (%BF). Testicular volume-for-age z-scores were used to classify "early," "average," or "late" maturing boys. Ordinal logistic regression analyses with a proportional odds model were applied to analyze the association between anthropometric variables and age-adjusted degree of pubertal development, with results expressed as age-adjusted odds ratios (AOR). Cumulative incidence curves for reaching pubertal milestones were stratified by BMI.

RESULTS

Boys with a low BMI for age (BMI_z  < -1) were less likely to have reached a pubertal testicular volume (USTV ≥ 2.7 mL) or a pubertal serum level of testosterone (≥0.5 nmol/L) compared to normal weight boys (AOR 0.3, p = 0.038, AOR 0.3, p = 0.026, respectively), and entered puberty on average with a delay of approximately eight months. Boys with high BMI for age (BMI_z  > 1) exhibited a comparable timing as normal weight boys. The same was found for WC. Pubertal markers were not associated with SSF or %BF.

CONCLUSION

By examining the association between puberty and weight status classified as low, average, or high, we found that a low BMI or WC for age were associated with a less advanced pubertal development and delayed timing of puberty in boys. No significant association was observed for a high BMI or WC. Moreover, no significant effects of SSF or %BF were observed. A low weight status should also be considered when assessing pubertal development in boys.

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.

Growth change in Polish women: Reduction of the secular trends?

The aim of the study was to analyse changes in the average height of adult Polish women born in 1931-2001 in the aspect of dynamically changing economic and socio-economic conditions of the living environment. An ethnically homogeneous group of 6,028 adult women from large Polish cities, born in 1931-2001, living between 1931 and 2020, were examined using the same research methods and research equipment. All women were divided into eight birth cohorts. The Kruskal-Wallis test and multiple regression analyses were used. Root Mean Square Standardized Effect (RMSSE), critical value of the test, and test power were calculated. The average height of women born during 70 years of the study increased by 9.63 cm, from 158.22 cm (SD = 5.57 cm) to 167.85 cm (SD = 6.91 cm) (H = 1084.84, p<0.001). The intensity of the intergenerational trend in subsequent cohorts of years of birth varied strongly between decades, averaging 1.34 cm/decade. The body height in women increased significantly up to the height of those born between 1970 and 1979 and then the trend weakened noticeably, although it remained positive. The observed secular trend confirms positive changes in the standard of living of Polish women between 1931 and 2020. Improving living conditions allow people to fully achieve their genetically determined growth potential.

Socio-Ecological Challenges as Modulators of Women's Reproductive Trajectories

Amenorrhea, anovulatory cycles, miscarriages, and other reproductive outcomes are often seen as pathological. Life history theory, in contrast, treats those outcomes as adaptations that helped women optimize the timing of reproductive ventures across our evolutionary history. Women's bodies adjust their reproductive strategies in response to socio-ecological conditions, a process mediated by the hypothalamic-pituitary-adrenal axis (HPAA). Here, we review the links between socio-ecological conditions, HPAA activity, and the pace of women's reproductive transitions such as puberty, age at first birth, interbirth interval, and perimenopause. We also discuss the HPAA's role as a modulator of reproductive function: It not only suppresses it but may also prime women's bodies for future reproductive ventures. We conclude by reviewing challenges and opportunities within our subfield, including the need for transdisciplinary teams to develop longitudinal studies to improve our understanding of women's reproductive trajectories and outcomes from the moment they are conceived.

Pulmonary diffusing capacity measured by NO/CO transfer in Tunisian boys

BACKGROUND

The diffusing capacity, which measures gas-exchange, uses reference values based on data from American or European studies. There are currently no reference values of pulmonary diffusing capacity (TL) and its components, such as the conductance of the membrane (Dm) and capillary lung volume (Vc) for healthy North African children.

OBJECTIVES

We determined the prediction equations-reference values for TL, Dm, Vc and the alveolar volume (VA) in healthy Tunisian boys.

METHODS

Values of Vc, Dm, TL, and VA were measured by the NO/CO transfer method, using a single breath maneuver in 118 Tunisian boys (8-14 years old) at rest. We performed linear regression analysis of the pulmonary parameters and independent variables, such as height, weight, and age.

RESULTS

The reference equations for pulmonary diffusing capacity for carbon monoxide (TL_CO ) was 0.201 × weight (kg) + 8.979; for TL_NO was 0.76 × height (cm)-24.383; for Dm was 0.388 × height (cm)- 12.555 and for VA was 0.34 × height (cm)-3.951. Vc increased significantly with weight (P < .05) but not with age (P > .05).

CONCLUSIONS

References norms for TL_CO and TL for nitric oxide and its components in young Tunisian boys are similar to data from other countries. The prediction equations we developed can be extended to clinical practice in Tunisia and can be considered for use in neighboring North African countries.

Menarche at an Earlier Age: Results from Two National Surveys of Israeli Youth, 2003 and 2016

STUDY OBJECTIVE

To assess emergent changes in the age at menarche and investigate associated factors in Israeli adolescents in 2003 and 2016.

DESIGN

Cross-sectional study.

SETTING

Two national representative school-based surveys (first and second "Mabat Youth").

PARTICIPANTS

Both surveys included female students in 7th-12th grades (ages 11-19 years). The first (N = 3328) was conducted between the years 2003 and 2004, and the second (N = 2535) from 2015 to 2016.

INTERVENTIONS

The survey questionnaire was self-administered and anthropometric measurements were performed by trained personnel.

MAIN OUTCOME MEASURES

The current age at menarche in Israeli girls was determined and independent factors (demographic, clinical, and lifestyle) examined. Changes that occurred since the past national survey more than a decade ago were documented.

RESULTS

The estimated median age at menarche declined from 13.0 (interquartile range, 12.0-14.0) years in 2003-2004 to 12.5 (interquartile range, 12.0-13.0) years in 2015-2016 (P < .0001). Jewish girls reached menarche earlier than Arab girls, but both populations experienced a similar downward trend in the past approximately 14 years. Greater body mass index, higher socioeconomic status, and immigrant status were associated with younger menarche onset (P < .001). Age at menarche remained lower in 2015-2016 vs 2003-2004, even after adjustment for these potential confounders, with a high hazard ratio (HR), which decreased as a function of survival time (t): HR_t = 15.417 × 0.813^t.

CONCLUSION

This study confirms the decline in age at menarche in Israel. Findings were associated with body mass index and population group but also indicated that other factors are likely involved.

Secular trend and social gradients in the menarcheal age of girls from eastern Poland between 1986 and 2016

The age at menarche is changing together with the development of society. The intensities of secular trends vary in different countries, regions or even towns and villages. Therefore, the objective of the paper was to assess the changes of the menarcheal age of girls in groups defined by different levels of parental education and the number of children in a family as well as the general index of socioeconomic status. The paper utilises the results of research conducted in the years 1985–1986, 2005–2006 and 2015–2016, covering 11 671 girls aged 10–16 from eastern provinces of Poland. Information about the date of birth, the date of the first period, place of residence, fathers’ and mothers’ education and the number of children in a family was collected. Research material was divided into groups stratified by mother’s education, father’s education, number of children in a family, size of place of residence and the general index of socioeconomic status (SES) was calculated. The results were processed statistically using one-way analysis of variance (ANOVA) and the Newman-Keuls method.

In all the assessed groups of girls the acceleration of maturation has been observed. Greater socio-economic differences of the menarcheal age of the respondents were observed in the years 1986–2006, whereas in the years 2006–2016 the differences were smaller. During the assessed period of 30 years, the most intensive acceleration in menarche was observed in the lowest social strata, i.e. in the daughters of parents with primary or vocational education, in those from the largest families and in those who were included in the group with the lowest SES point values. The lowest acceleration in the described indicator of development was found in girls from families with one or two children, whose parents had higher education degrees and the highest SES values.

The assessed schoolgirls still demonstrate the existence of social gradients in the menarcheal age but the gradients are smaller than 30 years ago.

Hypothalamic and Cell-Specific Transcriptomes Unravel a Dynamic Neuropil Remodeling in Leptin-Induced and Typical Pubertal Transition in Female Mice

Epidemiological and genome-wide association studies (GWAS) have shown high correlation between childhood obesity and advance in puberty. Early age at menarche is associated with a series of morbidities, including breast cancer, cardiovascular diseases, type 2 diabetes, and obesity. The adipocyte hormone leptin signals the amount of fat stores to the neuroendocrine reproductive axis via direct actions in the brain. Using mouse genetics, we and others have identified the hypothalamic ventral premammillary nucleus (PMv) and the agouti-related protein (AgRP) neurons in the arcuate nucleus (Arc) as primary targets of leptin action in pubertal maturation. However, the molecular mechanisms underlying leptin's effects remain unknown. Here we assessed changes in the PMv and Arc transcriptional program during leptin-stimulated and typical pubertal development using overlapping analysis of bulk RNA sequecing, TRAP sequencing, and the published database. Our findings demonstrate that dynamic somatodendritic remodeling and extracellular space organization underlie leptin-induced and typical pubertal maturation in female mice.

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MBH DEGs between lean and Lep^ob mice are highly represented in development

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Short-term leptin to Lep^ob mice alters MBH DEGs associated with reproduction

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PMv/Arc LepRb DEGs between lean and Lep^ob mice are abundant in extracellular space

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DEGs in developing PMv/Arc are conspicuous in extracellular and neuropil remodeling

Comparison of growth and nutritional status of Chinese and Japanese children and adolescents

BACKGROUND

The difference in growth and nutritional status, both important indices of population quality, between Chinese and Japanese children and adolescents is unknown.

AIM

This study aimed to compare growth and nutritional status between Chinese and Japanese children and adolescents.

SUBJECTS AND METHODS

The height-for-age and BMI-for-age distribution of 9,226 children and adolescents aged 7-18 years from China and Japan were described with the Lambda Mu and Sigma method. Wasting, overweight and obesity were evaluated based on BMI-for-age cut-offs of the 2007 WHO Child Growth Reference.

RESULTS

For boys, the overall average height, weight and BMI of Chinese participants were 3.0 cm, 4.8 kg and 1.2 kg/m² greater compared with Japanese participants, respectively; for girls, these were 4.6 cm, 3.9 kg and 0.6 kg/m², respectively. Compared with Japanese children, the 3rd, 50th and 97th percentiles of height-for-age, 1Z-score, and 2Z-score of BMI-for-age of Chinese children were greater, whereas the minus 2Z-scores of Chinese children were less. The prevalence of wasting, overweight and obesity among Chinese participants was greater.

CONCLUSIONS

Compared with Japanese children, Chinese children tended to be taller. The worrying burden of overweight, obesity and wasting was recognised among Chinese children.

PUBERTY IN A SAMPLE OF BRAZILIAN SCHOOLBOYS: ONSET AND ANTHROPOMETRIC CHARACTERISTICS

Objective:

To determine the age of puberty onset in boys and collect anthropometric data of participants at different puberty stages.

Methods:

This is a cross-sectional study that assessed 430 boys in a random sample representing 48,390 students from public and private schools from the city of Uberaba, Southeast Brazil. The inclusion criteria were males, aged between 5 and 18 years, and absence of previous diseases. Participants and their guardians filled a semistructured questionnaire with questions relevant to their and their parents’ puberty. We set the significance at p<0.05 and calculated the 95% confidence intervals.

Results:

The mean age found in the puberty stage G2 was 11.2±1.8 (95% of participants in stage G2 were 9.2-13.4 years old). Pubarche data showed a mean of age of 11.0±1.6 years (95% of the participants experienced pubarche when they were 8.0-14.0 years old). When compared to the confidence intervals of two classical studies on the subject, our results showed a trend toward earlier pubarche. In addition, the mean age of this event in the children’s parents was of 12.1±1.4 years, which was significantly higher than the age of the children’s pubarche (p<0.001).

Conclusions:

These results indicate a secular decreasing trend in pubarche age and an earlier puberty onset. Considering these parameters, is important to design public policies aimed at preventing these early events.

Recent pubertal timing trends in Northern Taiwanese children: Comparison with skeletal maturity

BACKGROUND

International studies have reported an early age of onset of puberty in girls and boys. However, the current situation of puberty onset in Taiwanese children is unknown. In this study, the timing of menarche and pubertal change in testicular volume (TV) in Taiwanese children was examined, and bone age (BA) was used as an internal somatic maturity scale and compared with the chronological age (CA) at pubertal timing.

METHODS

Clinical data from October 1, 2010, to March 31, 2018, were retrospectively collected from a general hospital in Taipei. The data of patients who were diagnosed with endocrine/genetic disorders were excluded. Clinical data included CA, timing of menarche, and X-ray images of TV and BA. BA was determined by a senior pediatrician and a senior pediatric radiologist. The reliability and validity of BA readings were tested. Collected data were analyzed statistically.

RESULTS

Overall, TV records of 241 boys and the menarche timing data of 98 girls were collected from 1823 children. CA for menarche was 11.35 ± 1.06 years (mean ± SD), and BA for menarche was 12.95 ± 0.80 years. CA and BA at TV = 15 mL in male puberty was 12.32 ± 1.22 and 13.46 ± 0.68 years, respectively. A stronger correlation was observed between TV and BA than between TV and CA during the pubertal period.

CONCLUSION

The secular trend of earlier puberty timing continues. The decline rate of menarche timing was approximately 0.43 years per decade in the past 30 years. Among boys, an advance of more than 1 year in pubertal timing age was observed over the past 20 years. BA and TV showed high correlation during puberty.

Reproductive Health and Metabolic Parameters in Women with Type 2 Diabetes

Aim: This study evaluated the correlations between metabolic parameters and reproductive health data in women with type 2 diabetes mellitus (T2DM).

Material and methods: In this observational retrospective study, data from the medical records of 324 adult women with T2DM attending their regular diabetes check-ups were collected and analyzed (i.e., anthropometric parameters at first outpatient visit and yearly thereafter, first recorded HbA1c and all HbA1c for the entire follow-up duration, as well as obstetrical/gynecological information).

Results: Age at the diagnosis of T2DM correlated positively with age at menarche (r = 0.21, [95% CI: 0.09, 0.31], p = 0.0002) and age at menopause (r = 0.18 [95% CI: 0.07, 0.29], p <0.01). Age at menarche correlated negatively with mean weight (r = –0.21 [95% CI: –0.31, –0.10], p: 0.0002) and mean BMI (–0.22 [–0.32, –0.11], p <0.0001) over the follow-up time. Patients with shorter time difference between age at menarche and age at onset of T2DM (≤45 years) had higher mean weight (83.8 ± 14.5 kg vs. 78.4 ± 16.0 kg, p = 0.0001), BMI (33.2 ± 5.6 kg/m2 vs. 31.8 ± 5.7 kg/m2, p <0.05), and HbA1c over time (6.9 ± 0.8% vs. 6.6 ± 0.9%, p <0.0001). Women with T2DM with earlier menarche (<12 years old), with irregular menses during their reproductive life, and ≥3 pregnancies had higher overall BMI, but mean HbA1c were not significantly different. However, women diagnosed with T2DM before menopause had a higher mean HbA1c over time (7.1 ± 0.8% vs. 6.7 ± 0.9%, p <0.01).

Conclusion: The BMI correlated with several indicators of reproductive health (earlier menarche, irregular menses, and higher number of pregnancies), while earlier onset of T2DM influenced metabolic control in women with T2DM.

Indicators of nutritional status and physical activity level as factors associated with the onset of menarche of ten year old girls from Zadar county, Croatia

OBJECTIVES

The aim is to determine the differences in nutritional status and level of physical activity (PA) of ten year old menstruating and non-menstruating girls.

METHODS

On the sample of 208 girls, fourth graders of elementary schools in Croatia, the indicators of nutritional status were measured: body mass index(BMI), body fat % and waist to hip ratio(WHR), while the PA was assessed using PAQ-C questionnaire. Welch´s t-test was applied to establish the differences and multivariate regression analysis was applied to establish the relationships.

RESULTS

Menstruating girls have significantly higher body mass (43.42 kg±8.31 vs. 38.64 kg±8.33), waist circumference (68.10 cm ± 9.86 vs. 62.22 cm ± 7.16), hip circumference (80.81 cm ± 7.24 vs. 76.63 cm ± 7.7), BMI (19.70 ± 3.42 vs. 17.74 ± 3.10), body fat % (28.05 ± 7.54 vs. 21.98 ± 7.67) and WHR (0.84 ± 0.06 vs. 0.81 ± 0.05) in comparison to non-menstruating girls, while non-menstruating girls have significantly higher PA level (2.93 ± 0.57 vs. 2.68 ± 0.57). The regression analysis have shown a significant relationship between body fat % and the onset of menarche (β=-0.23, SEβ=0.07, p<0.01).

CONCLUSIONS

Results show differences in the indicators of nutritional status of girls with regard to the status of maturity. Increased nutritional status and body fat % may be indicators of the accelerated developmental tempo and a determinant for the earlier onset of menarche.

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.

Secular trends in age at menarche in 20th century Mexico: Differences by ethnicity, area of residency, and socioeconomic status

OBJECTIVES

This study aims to assess the secular trend in age at menarche (AAM) in Mexico over the 20th century, and compare the patterns according to area of residence (rural/urban), socioeconomic status (SES), and ethnicity (indigenous/nonindigenous).

METHODS

Data on AAM from 24 380 women aged ≥20 years born between 1906 and 1986 were obtained from the Mexican National Health and Nutrition Survey 2006. Birth cohorts were compared to test for a secular trend and differences in mean AAM by area of residence, SES, and ethnicity were evaluated using the Welch test for heterogeneous variances followed by Tamhane T² for post hoc comparisons.

RESULTS

Mean AAM declined from 13.3 years among Mexican women born before the 1940s to 12.56 years among those born in the 1980s. Across birth cohorts, urban women had significantly earlier AAM than their rural counterparts. Nonindigenous urban women reached menarche the earliest and rural indigenous women the latest of all groups. Nonindigenous urban residents experienced a comparatively earlier decline, while that for the indigenous rural women occurred last. High SES women reached menarche the earliest and low SES women the latest. The historical decline in AAM for high and medium SES groups occurred relatively early, whereas that for the low SES occurred last.

CONCLUSIONS

Mean AAM was associated with area of residence, ethnicity, and SES. Our findings indirectly suggest that advances in living conditions experienced in Mexico during the 20th century appear to have been insufficient to overcome the social and biological inequalities accumulated over centuries in some groups.

Secular trend in age at menarche in women in Portugal born between 1920 and 1992: Results from three population-based studies

OBJECTIVES

Worldwide data on age at menarche suggest a gradually earlier maturation, which is stabilizing in some societies. The interplay between socioeconomic, behavioral, and environmental factors generates uncertainty about the current status and future trend of age at menarche in most societies. Therefore, we aimed to describe trends in age at menarche during the 20th century in Portugal.

METHODS

A sample of 11 274 women born between 1920 and 1992 in northern Portugal, recruited to participate in three population-based cohorts (EPIPorto, EPITeen, and Generation XXI) was evaluated. Age at menarche across birth year categories was compared using ANOVA and the rate of change over time using linear regression.

RESULTS

Age at menarche decreased with birth year (-31.1 days per 5 years; β = -.017, P < .001), women born before 1930 having a significantly higher age at menarche than those who were born after 1990 (mean (SD) = 13.1 (1.83) vs 12.0 (1.25), P < .001).

CONCLUSIONS

The decrease in age at menarche in northern Portugal suggests that a plateau is yet to be reached. Attention to time trends in age at menarche is relevant for health promotion since there is a possible relationship between pubertal timing and the later development of the metabolic syndrome.

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).