Interactions Between Genetic, Prenatal Substance Use, Puberty, and Parenting are Less Important for Understanding Adolescents' Internalizing, Externalizing, and Substance Use than Developmental Cascades in Multifactorial Models.

This study tested interactions among puberty-related genetic risk, prenatal substance use, harsh discipline, and pubertal timing for the severity and directionality (i.e., differentiation) of externalizing and internalizing problems and adolescent substance use. This is a companion paper to Marceau et al. (2021) which examined the same influences in developmental cascade models. Data were from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort (n = 4504 White boys, n = 4287 White girls assessed from the prenatal period through 18.5 years). We hypothesized generally that later predictors would strengthen the influence of puberty-related genetic risk, prenatal substance use exposure, and pubertal risk on psychopathology and substance use (two-way interactions), and that later predictors would strengthen the interactions of earlier influences on psychopathology and substance use (three-way interactions). Interactions were sparse. Although all fourteen interactions showed that later influences can exacerbate or trigger the effects of earlier ones, they often were not in the expected direction. The most robust moderator was parental discipline, and differing and synergistic effects of biological and socially-relevant aspects of puberty were found. In all, the influences examined here operate more robustly in developmental cascades than in interaction with each other for the development of psychopathology and transitions to substance use.

Integrating context in the examination of pubertal timing effects on disordered eating among Black and Latinx girls.

Earlier pubertal onset has been associated with increased disordered eating symptoms in cisgender girls. Although this finding has been replicated across studies of disordered eating, most studies have focused on white samples. The lack of studies is surprising given that early pubertal timing may impact disordered eating risk in Black and Latinx girls differently due to trends of earlier pubertal onset in these groups and increased stressors related to interpersonal and structural racism and economic marginalization. Current methods of examining pubertal timing among Black and Latinx girls may also not fully capture their experience. Contextual factors (e.g., neighborhood and school racial/ethnic composition) may influence how minoritized girls both perceive and are affected by their pubertal timing. Moreover, factors such as ethnic-racial identity development and experiences of discrimination may be important mechanisms explaining the association between pubertal timing and disordered eating risk. This paper aims to provide a brief overview of studies examining pubertal timing and disordered eating risk among Black and Latinx girls in the US and to discuss recommendations for future research that integrate contextual factors in the examination of pubertal timing and its effects. PUBLIC SIGNIFICANCE: Early pubertal timing has been associated with increased risk of disordered eating symptoms among cisgender girls; however, studies have been limited due to the use of predominantly white samples. The article provides a brief overview of findings related to pubertal timing effects among Black and Latinx girls, discusses considerations for the measurement of pubertal timing, and highlights the need for inclusion of contextual factors in future research.

Pubertal timing in adolescents with ADHD: extension and replication in an all-female sample.

Pubertal timing predicts a miscellany of negative mental and physical health outcomes. Prior work examining pubertal timing in youth with attention-deficit hyperactivity disorder (ADHD) has failed to investigate potential sex specificity of results. Therefore, we aim to extend past findings in a sample of female adolescents with ADHD. We compare pubertal timing (1) between females with and without carefully diagnosed ADHD and (2) between females with ADHD who do vs. do not have a history of stimulant medication use during childhood. We examine 127 adolescent females with childhood-diagnosed ADHD and 82 matched neurotypical peers (Mage: 14.2 years, range: 11.3-18.2) from the Berkeley Girls with ADHD Longitudinal Study (Wave 2). We measured pubertal timing using self-reported Tanner staging and age at menarche. Three strategies compared pubertal timing across groups: (1) χ 2 tests of Tanner Stages, (2) t tests of residuals of pubertal status regressed on age, and (3) t tests of age at menarche. Pubertal timing of girls with and without ADHD did not differ significantly across methods and measures. Yet females with ADHD who had received stimulant medication during childhood menstruated later than those without a stimulant history, potentially related to differences in BMI across groups. On the other hand, no significant differences between medicated vs. non-medicated participants emerged for the two Tanner staging indicators. Our findings extend prior work, suggesting that females with ADHD are developing physically at a similar time as their peers, which parallels findings from previous mixed-sex samples that did not examine effects separately by sex.

Corticolimbic connectivity mediates the relationship between pubertal timing and mental health problems.

BACKGROUND: Undergoing puberty ahead of peers ('earlier pubertal timing') is an important risk factor for mental health problems during early adolescence. The current study examined pathways between pubertal timing and mental health via connectivity of neural systems implicated in emotional reactivity and regulation (specifically corticolimbic connections) in 9- to 14-year-olds. METHOD: Research questions were examined in the Adolescent Brain Cognitive Development (ABCD) Study, a large population representative sample in the United States. Linear mixed models examined associations between pubertal timing and resting-state corticolimbic connectivity. Significant connections were examined as potential mediators of the relationship between pubertal timing and mental health (withdrawn depressed and rule-breaking) problems. Exploratory analyses interrogated whether the family environment moderated neural risk patterns in those undergoing puberty earlier than their peers. RESULTS: Earlier pubertal timing was related to decreased connectivity between limbic structures (bilateral amygdala and right hippocampus) and the cingulo-opercular network, left amygdala and somatomotor (mouth) network, as well as between the left hippocampus and ventral attention network and visual network. Corticolimbic connections also mediated the relationship between earlier pubertal timing and increased withdrawn depressed problems (but not rule-breaking problems). Finally, parental acceptance buffered against connectivity patterns that were implicated in withdrawn depressed problems in those undergoing puberty earlier than their peers. CONCLUSION: Findings highlight the role of decreased corticolimbic connectivity in mediating pathways between earlier pubertal timing and withdrawn depressed problems, and we present preliminary evidence that the family environment may buffer against these neural risk patterns during early adolescence.

Pubertal timing and adolescent outcomes: investigating explanations for associations with a genetically informed design.

BACKGROUND: Psychopathology and risky behaviors increase during adolescence, and understanding which adolescents are most at risk informs prevention and intervention efforts. Pubertal timing relative to same-sex, same-age peers is a known correlate of adolescent outcomes among both boys and girls. However, it remains unclear whether this relation is better explained by a plausible causal process or unobserved familial liability. METHODS: We extended previous research by examining associations between pubertal timing in early adolescence (age 14) and outcomes in later adolescence (age 17) in a community sample of 2,510 twins (49% boys, 51% girls). RESULTS: Earlier pubertal timing was associated with more substance use, risk behavior, internalizing and externalizing problems, and peer problems in later adolescence; these effects were small, consistent with previous literature. Follow-up co-twin control analyses indicated that within-twin-pair differences in pubertal timing were not associated with within-twin-pair differences in most adolescent outcomes after accounting for shared familial liability, suggesting that earlier pubertal timing and adolescent outcomes both reflect familial risk factors. Biometric models indicated that associations between earlier pubertal timing and negative adolescent outcomes were largely attributable to shared genetic liability. CONCLUSIONS: Although earlier pubertal timing was associated with negative adolescent outcomes, our results suggests that these associations did not appear to be caused by earlier pubertal timing but were likely caused by shared genetic influences.

Critical body fat percentage required for puberty onset: the Taiwan Pubertal Longitudinal Study.

PURPOSE: Prepubescent body fat percentage (BFP) is associated with puberty onset; however, the association between the timing of puberty onset and BFP remains unclear. This study aimed to determine whether and how the timing of puberty onset is associated with various anthropometric measures, and to investigate the critical time period of the BFP transition before and after puberty. METHODS: The Taiwan Pubertal Longitudinal Study (TPLS) has a multicenter, population-based prospective cohort and was established in July 2018 at 4 pediatric departments. We included girls aged 6-14 years and boys aged 9-17 years evaluated as having puberty onset and excluded those with precocious puberty diagnosis. The anthropometric measures were collected every 3 months. The main outcome was age at puberty onset. Data were analyzed between July 2018 and September 2020. RESULTS: For 153 girls and 83 boys, BFP was significantly related to puberty onset for girls. Longitudinal analysis revealed that BFP in the girls was reduced to less than 18% 6 months before puberty and rapidly increased by 2.85% over 3 months, then exceeding 20% before puberty onset. After puberty onset, BFP was no longer lower than 22%. CONCLUSIONS: BFP is an essential predictor of age at puberty onset. BFP first decreases and then begins to increase 3-6 months before puberty in girls. Parents and schools could monitor the BFP of prepubescent girls every 6 months to predict puberty onset.

Pubertal timing moderates the same-day coupling between family hassles and negative affect in girls and boys.

This study examined the association between pubertal timing, daily affect, conduct problems, and the exposure to hassles across family, peer, and school contexts. Adolescents (M age = 12.27; 49.7% female; 62.6% White) completed ecological momentary assessments across 14 consecutive days (N = 388). Earlier maturing girls reported lower daily averages of positive affect compared to their same-sex, same-age peers. We did not find evidence for a relationship between pubertal timing and daily negative affect or conduct problems in girls, nor for daily negative and positive affect or conduct problems in boys. However, pubertal timing did moderate the day-level association between average negative affect and family hassles for both girls and boys. When experiencing more family hassles, earlier maturing girls reported greater negative affect relative to later maturing girls who experienced family hassles. In contrast, later maturing boys, relative to earlier maturing boys, reported higher levels of negative affect in the context of family hassles.

Pubertal maturation and timing effects on resting state electroencephalography in autistic and comparison youth.

Autistic and comparison individuals differ in resting-state electroencephalography (EEG), such that sex and age explain variability within and between groups. Pubertal maturation and timing may further explain variation, as previous work has suggested alterations in pubertal timing in autistic youth. In a sample from two studies of 181 autistic and 94 comparison youth (8 years to 17 years and 11 months), mixed-effects linear regressions were conducted to assess differences in EEG (midline power for theta, alpha, and beta frequency bands). Alpha power was analyzed as a mediator in the relation between pubertal maturation and timing with autistic traits in the autistic groups to understand the role of puberty in brain-based changes that contribute to functional outcomes. Individuals advanced in puberty exhibited decreased power in all bands. Those who experienced puberty relatively early showed decreased power in theta and beta bands, controlling for age, sex, and diagnosis. Autistic individuals further along in pubertal development exhibited lower social skills. Alpha mediated the relation between puberty and repetitive behaviors. Pubertal maturation and timing appear to play unique roles in the development of cognitive processes for autistic and comparison youth and should be considered in research on developmental variation in resting-state EEG.

Association between exposure to persistent organic pollutants and pubertal timing in boys and girls: A systematic review and meta-analysis.

In recent years, the phenomenon of abnormal pubertal timing in children has become increasingly common worldwide. Persistent organic pollutants (POPs) may be one of the risk factors contributing to this phenomenon, but the relationship between them is unclear based on current evidence. The purpose of this study was to determine the association of POPs exposure with pubertal timing in girls and boys by conducting a systematic review and meta-analysis. We searched PubMed and Embase databases for studies before June 1, 2023. Meta-analysis was performed by pooling relative risk (RR) or odds ratio (OR) or prevalence ratio (PR) or hazard ratio (HR) estimates with 95 % confidence intervals (CIs). Subgroup analysis, publication bias assessment and sensitivity analysis were also carried out. A total of 21 studies were included, involving 2479 boys and 8718 girls. The results of meta-analysis showed that exposure to POPs was significantly associated with delayed pubertal timing in girls (RR: 0.85; 95 % CI: 0.79-0.91; p < 0.001). There was no statistically significant association between exposure to POPs and pubertal timing in boys (RR: 1.18; 95 % CI: 0.99-1.40; p = 0.070). Subgroup analysis showed that there may be gender differences in the effects of exposure to POPs on pubertal timing. Our results suggested that exposure to POPs could delay pubertal timing in girls. However, based on current evidence, no significant association was found between POPs exposure and pubertal timing in boys.

The Effects of Pubertal Timing on Academic Performance in Adolescence and Career Success in Adulthood: Evidence from a 16-year Longitudinal Study.

Previous research showed inconsistent effects of pubertal timing on adolescent academic performance and adult career success. Moreover, the relative importance of biological vs. perceived pubertal timing has not been examined. This study examined effects of biological and perceived pubertal timing on academic performance throughout adolescence and career success in adulthood together with sex differences in an understudied population of pre-dominantly Black youth from lower income families. The sample included 704 youth (52% male, 76% Black, 22% White) interviewed at four time points (Mean ages: 11.8, 13.2, 17.6, and 27.7 years). The results from a mediation path model showed that among males, perceived off-time pubertal timing uniquely predicted lower concurrent academic performance as well as lower objective career success in adulthood; this effect was mediated by lower academic performance throughout adolescence. Additionally, results from bivariate correlation analyses showed associations between early biological pubertal timing and lower concurrent academic performance in males and early perceived pubertal timing and lower concurrent academic performance among females. These findings contribute to the understanding of more nuanced links between pubertal timing, academic performance and subsequent career success in an understudied population of pre-dominantly Black youth from lower income families.

The Effect of Relative Pubertal Maturation and Perceived Popularity on Symptoms of Depression and Social Anxiety in Adolescent Boys and Girls.

Research has shown that adolescents - particularly girls - who mature relatively early often experience more internalizing problems. This effect is thought to be partially driven by psychosocial mechanisms, but previous research based relative pubertal maturation on complete samples or population standards, instead of considering the adolescents' direct peer environment. In the current study the level of adolescents' pubertal development was assessed relative to their classmates in order to examine relative pubertal maturation. The effects of adolescents' relative pubertal status, and their perceived popularity, on symptoms of social anxiety and depression in adolescents were studied. All analyses were also performed for absolute pubertal maturation. Participants were 397 young adolescents (Mage = 13.06, SD = 0.36, 49.9% girls) at timepoint 1, and 307 (Mage = 14.08, SD = 0.36, 50.5% girls) at timepoint 2. A significant positive relationship was found between relative pubertal timing and symptoms of depression for girls but not boys. Social anxiety symptoms were not significantly related to relative pubertal timing in either sex. Relative pubertal maturation had no effect on change in or persistence of depressive and social anxiety symptoms one year later. The effects of the comparison with the immediate peer environment, did not seem to explain more variance in internalizing symptoms than the effects of early maturation.

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OBJECTIVES: To study the association between early-life factors (including birth weight, method of birth, gestational age, and history of gestational metabolic disorders) and pubertal timing in girls. METHODS: The stratified cluster sampling method was used to select the girls in grades 2-3 and 7-8 from three primary schools and three middle schools in Guangzhou, China from March to December, 2019, and breast development was examined for all girls. A questionnaire survey was performed to collect the information on early-life factors. The multivariate logistic regression model was used to evaluate the association of gestational metabolic disorders, birth weight, method of birth, and gestational age with pubertal timing in girls. The Bootstrap method was used to assess the mediation effect of body mass index (BMI) (Z score) between high birth weight (≥4 000 g) and pubertal timing. RESULTS: A total of 1 665 girls were enrolled, among whom 280 (16.82%) were judged to have early pubertal timing. The multivariate logistic regression analysis showed that high birth weight was associated with the increased risk of early pubertal timing (OR=2.12, 95%CI: 1.19-3.66, P=0.008). Nevertheless, no significant association was observed between other early-life factors and pubertal timing (P>0.05). The OR for the mediation effect of BMI (Z score) between high birth weight and early pubertal timing was 1.25 (95%CI: 1.09-1.47), accounting for 29.33% of the total effect of high birth weight on early pubertal timing. CONCLUSIONS: High birth weight is associated with the increased risk of early pubertal timing in girls, and overweight/obesity may play a partial mediating role in the association between high birth weight and early pubertal timing in girls.

Family environmental antecedents of pubertal timing in girls and boys: A review and open questions.

Across nonhuman species, pubertal timing is affected by the social environment, with consequences for reproductive success and behavior. In human beings, variations in pubertal timing have not been systematically examined in relation to social environmental antecedents, although their psychological consequences are well documented. This paper focuses on links in human beings between pubertal timing and the childhood social environment, with several sections: A review of studies relating pubertal timing to the family context, a key aspect of the social environment; challenges in studying the issue; and opportunities for future work that takes advantage of and creates links with evidence in other species. The review shows that pubertal timing in girls is accelerated by adversity in aspects of the early family social context, with effects small in size; data in boys are not sufficient to enable conclusions. Inferences from existing studies are limited by variations in conceptualizations and measurement of relevant aspects of puberty and of the family social environment, and by methodological issues (e.g., reliance on existing data, use of retrospective reports, nonrandom missing data). Open questions remain about the nature, mechanisms, and specificity of the links between early family social environment and pubertal timing (e.g., form of associations, consideration of absence of positive experiences, role of timing of exposure). Animal studies provide a useful guide for addressing these questions, by delineating potential hormonal mechanisms that underlie links among social context, pubertal timing, and behavior, and encouraging attention to aspects of the social environment outside the family, especially peers.

Current situation of menstruation and gynecological diseases prevalence among Chinese women: a cross-sectional study.

BACKGROUND: Gynecological diseases have been taken attention and studied worldwide. Although, no recent studies have delineated the magnitude of gynecological diseases among Chinese women. This study aims to evaluate the current situation of menstruation and gynecological diseases prevalence among Chinese women. METHODS: A cross-sectional study was conducted at a hospital affiliated with Nanjing medical university in Nanjing, China between September 2021 and February 2022. A sample size of 977 women aged 18-52 years participated in a face-to-face interview questionnaire. Logistic regression was performed to determine whether pubertal timing and menstrual characteristics were associated with gynecological diseases. RESULTS: The most prevalent gynecological disease was dysmenorrhea (45.96%), followed by polycystic ovary syndrome, PCOS (19.04%), uterine fibroids (14.23%), spontaneous abortion (13.20%), trouble conceiving (12.59%), ovarian dysfunction (11.16%) and endometriosis (4.09%). In the adjusted model, heavy bleeding with large clots was associated with an increased risk of dysmenorrhea (odds ratio, OR = 5.01, 95% Confidence interval, CI 2.26, 11.10; p = 0.000), while history of precocious puberty diagnosis was associated with a reduced risk of dysmenorrhea (OR = 0.50, 95%CI: 0.26, 0.94; p = 0.031). Regular menstrual cycle in the past 12 months and regular menstrual periods were associated with decreased risk of PCOS (OR = 0.44, 95%CI 0.30, 0.65; p = 0.000) and (OR = 0.52, 95%CI 0.36, 0.74; p = 0.000), respectively. Histories of early thelarche, early menarche, and precocious puberty diagnosis were associated with increased risk of ovarian dysfunction (OR = 1.96, 95%CI 1.25, 3.08, p = 0.004), (OR = 2.26, 95%CI 1.24, 4.13; p = 0.008) and (OR = 2.79, 95%CI 1.36, 5.74; p = 0.005), respectively. Heavy bleeding and heavy bleeding with large clots were associated with endometriosis (OR = 4.92, 95%CI 1.50, 16.15, p = 0.009) and (OR = 5.67, 95%CI 1.42, 22.56; p = 0.014), respectively. CONCLUSIONS: The prevalence of gynecological diseases is increasing among Chinese women and pubertal timing and menstrual characteristics may be associated with some gynecological diseases, specifically dysmenorrhea, PCOS, ovarian dysfunction, and endometriosis.

Ethnic-Racial Socialization Among Mothers of Black and Black-White Biracial Daughters During the Pubertal Transition.

Ethnic-racial socialization is a salient component of parenting in Black families. What is less clear is how Black families discuss ethnicity-race and social inequalities with pubescent children. We examined associations between pubertal timing and ethnic-racial socialization among mothers (Mage = 42) of Black (n = 286) and Black-White biracial (n = 233) girls aged 9-12. Moderation by maternal stress about puberty was also examined. Results indicated mothers of Black girls who were stressed about puberty reported more preparation for bias; whereas both groups of mothers reported more cultural socialization. Early pubertal timing and high maternal stress about puberty predicted more cultural socialization among both groups and more egalitarian beliefs among only mothers of Black-White biracial girls. The findings highlight the importance of ethnic-racial socialization during puberty.

The Distinct Roles of Biological and Perceived Pubertal Timing in Delinquency and Depressive Symptoms from Adolescence to Adulthood.

Pubertal timing is a robust predictor of externalizing and internalizing problems in adolescence, but controversies remain whether only early or off-time (both early and late) pubertal timing is associated with negative developmental outcomes and whether effects differ across perceptions of pubertal timing and actual biological pubertal timing. Additionally, less is known about the longevity of pubertal timing effects and mediators of effects that persist through adolescence and into adulthood. This longitudinal study investigated the effects of early and off-time pubertal timing, in form of perceived pubertal timing relative to peers and reported biological pubertal timing relative to age, on delinquency and depressive symptoms in adolescence and young adulthood between 2003 and 2022. Peer deviance and school connectedness were examined as mediators of any persisting effects. The sample included 704 youth (52% male, 76% African American, 22% Non-Hispanic White) who were assessed at four time points from early adolescence (Mean ages: 11.8, 13.2) to late adolescence (Mean age: 17.6) and young adulthood (Mean age: 27.7). Perceived off-time pubertal timing in males and early biological pubertal timing in both males and females were risk factors for persistent delinquency into young adulthood, but neither form of pubertal timing was associated with depressive symptoms. None of the effects were mediated by peer deviance or school connectedness. These findings advance the understanding of more nuanced effects of pubertal timing on adjustment problems in diverse youth as they develop from early adolescence to adulthood.

The association between pubertal timing and quality of life among children and adolescents: a cross-sectional study in Chongqing, China.

BACKGROUND: To determine the relationship between pubertal timing and quality of life (QOL) in children and adolescents and to provide a basis for QOL intervention in pubertal children in the future to promote good adaptation and healthy physical and mental development of children. METHODS: The survey was conducted in one county using a stratified cluster sampling method. The five physiological change items of the Puberty Development Scale (PDS) were used to assess the timing of puberty in students. Compared to students of the same age and the same sex, students who scored higher than the mean + standard deviation (SD) of individual developmental scores were defined as an early pubertal timing group. A 39-item QOL Scale for Children in Puberty was used to assess the QOL of the respondents. Multiple linear regression models were fitted separately for boys and girls. RESULTS: Of the 7223 students, 3754 (51.97%) were boys and 3469 (48.03%) were girls. The prevalence of early pubertal periods was 16.07%. The total QOL score in the early pubertal timing group (137.16 ± 18.67) was significantly lower than in the normal (on time) group (142.02 ± 17.98) and the late group (142.76 ± 18.35) (F = 37.311, P < 0.001). A multiple linear regression model showed that early pubertal timing was a risk factor for QOL (P < 0.0014), compared with normal and late pubertal timing. CONCLUSIONS: The early pubertal timing was associated with poorer QOL in children and adolescents. More attention should be paid to children with early pubertal timing in intervening children's QOL during pubertal development. Future longitudinal studies are needed to confirm the association between pubertal timing and QOL.

Developmental Cascades from Polygenic and Prenatal Substance Use to Adolescent Substance Use: Leveraging Severity and Directionality of Externalizing and Internalizing Problems to Understand Pubertal and Harsh Discipline-Related Risk.

The current study leveraged the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort (n = 4504 White boys, n = 4287 White girls assessed from the prenatal period through 18.5 years of age) to test a developmental cascade from genetic and prenatal substance use through pubertal timing and parenting to the severity of (regardless of type) and directionality (i.e., differentiation) of externalizing and internalizing problems to adolescent substance use. Limited associations of early pubertal timing with substance use outcomes were only observable via symptom directionality, differently for girls and boys. For boys, more severe exposure to prenatal substance use influenced adolescent substance use progression via differentiation towards relatively more pure externalizing problems, but in girls the associations were largely direct. Severity and especially directionality (i.e., differentiation towards relatively more pure externalizing problems) were key intermediaries in developmental cascades from parental harsh discipline with substance use progressions for girls and boys.

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

BACKGROUND: Breast feeding has been associated with improved infant health, but its impact on pubertal timing remains uncertain, particularly in boys. OBJECTIVE: The objective of this study was to investigate the association between duration of breast feeding and pubertal timing in boys and girls. METHODS: This population-based cohort study included 13 511 boys and girls from the Puberty Cohort nested within the Danish National Birth Cohort. The children gave half-yearly, self-reported information on pubertal development through questionnaires (Tanner stages, age at menarche, first ejaculation, voice break, axillary hair growth, and acne). Information on breast feeding was provided by the mothers when the children were 6 months of age. We estimated mean differences (in months) in age at attaining each pubertal marker and for overall timing of puberty (combined estimate) for every additional month of exclusive breast feeding. Furthermore, we estimated differences in pubertal age when comparing children never exclusively breastfed and exclusively breastfed <4 months using children exclusively breastfed ≥4 months as reference. In sub-analyses, we further adjusted for infant weight gain and childhood BMI at 7 years to investigate whether these variables mediated the association. RESULTS: Boys tended to reach pubertal markers later for every additional month of exclusive breast feeding (combined estimate: 0.2 (95% confidence interval [CI] 0.0, 0.4 months). Never exclusively breastfed boys reached pubertal markers earlier than the boys exclusively breastfed ≥4 months (combined estimate: -4.1 (95% CI -6.7, -1.6) months). Boys exclusively breastfed <4 months also reached pubertal markers earlier than those never exclusively breastfed but with smaller differences. In girls, duration of breast feeding was not associated with pubertal development. When including infant weight gain or childhood BMI, the results remained essentially unchanged. CONCLUSIONS: Shorter duration of exclusive breast feeding was associated with earlier pubertal development in boys but not in girls.

Associations of prenatal exposure to polycyclic aromatic hydrocarbons with pubertal timing and body composition in adolescent girls: Implications for breast cancer risk.

BACKGROUND: While animal data support an association between prenatal exposure to endocrine disrupting chemicals (EDCs) and altered mammary gland development and tumorigenesis, epidemiologic studies have only considered a few classes of EDCs in association with pubertal growth and development in girls. Polycyclic aromatic hydrocarbons (PAH) are a class of EDCs that have not been rigorously evaluated in terms of prenatal exposure and pubertal growth and development in girls. OBJECTIVE: In a New York City birth cohort of Black and Hispanic girls (n = 196; recruited 1998-2006), we examined associations of prenatal PAH exposure with self-reported age at growth spurt onset, breast development onset and menarche, and clinical measures of adolescent body composition including body mass index, waist-to-hip ratio, and body fat measured at ages 11-20 years. METHODS: We measured prenatal exposure to PAH using personal air monitoring data collected from backpacks worn by mothers during the third trimester of pregnancy (data available for all 196 girls) and biomarkers of benzo[α]pyrene-DNA adducts in umbilical cord blood (data available for 106 girls). We examined associations of prenatal PAH with the timing of pubertal milestones and adolescent body composition (11-20 years) using multivariable linear regression models adjusted for race/ethnicity, household public assistance status at birth, and age at outcome assessment. We also fit models further adjusted for potential mediators, including birthweight and childhood body size (BMI-for-age z-score measured at 6-8 years). RESULTS: Girls in the highest versus lowest tertile of ambient exposure to PAH, based on a summary measure of eight carcinogenic higher-molecular weight non-volatile PAH compounds (Σ8 PAH), had a 0.90 year delay in growth spurt onset (95% confidence interval (CI) = 0.25, 1.55; n = 196), a 0.35 year delay in breast development onset (95% CI = -0.26, 0.95; n = 193), and a 0.59 year delay in menarche (95% CI = 0.06, 1.11; n = 191) in models adjusted for race/ethnicity and household public assistance at birth. The statistically significant associations for age at growth spurt onset and menarche were not impacted by adjustment for birthweight or childhood body size. No differences in BMI-for-age z-score, waist-to-hip ratio, or percent body fat were found between girls in the highest versus lowest tertile of ambient Σ8 PAH. Results were similar when we evaluated benzo[α]pyrene-DNA adduct levels. DISCUSSION: Our results suggest that prenatal exposure to PAH might delay pubertal milestones in girls, but findings need to be replicated in other cohorts using prospectively collected data on pubertal outcomes.