Prenatal and postnatal exposures to endocrine disrupting chemicals and timing of pubertal onset in girls and boys: a systematic review and meta-analysis.

BACKGROUND: Globally, the ages at pubertal onset for girls and boys have been decreasing during recent decades, partly attributed to excess body fat accumulation. However, a growing body of literature has recognized that endocrine disrupting chemicals (EDCs) may play an important role in this global trend, but the association has not yet been fully established. OBJECTIVE AND RATIONALE: EDCs can interfere with normal hormone function and metabolism and play a role in pubertal onset. We aimed to systematically identify and evaluate the current evidence on the timing of pubertal onset in girls and boys following prenatal or postnatal exposures to xenobiotic EDCs. SEARCH METHODS: Following PRISMA guidelines, we performed a systematic literature search of original peer-reviewed publications in the PubMed database through a block search approach using a combination of index MeSH and free text search terms. Publications were considered if they covered biomarkers of prenatal or postnatal exposures to xenobiotic EDCs (European Commission's list of category 1 EDCs) measured in maternal or child biospecimen and pubertal onset defined by the progression of the following milestones (and assessed in terms of the following measures): menarche (age), thelarche (Tanner staging) and pubarche (Tanner staging), in girls, and genital stage (Tanner staging), testicular volume (ml) and pubarche (Tanner staging), in boys. OUTCOMES: The literature search resulted in 703 references, of which we identified 52 publications fulfilling the eligibility criteria for the qualitative trend synthesis and 23 publications for the meta-analysis. The qualitative trend synthesis provided data on 103 combinations of associations between prenatal or postnatal exposure to EDC compounds groups and puberty outcomes and the meta-analysis enabled 18 summary risk estimates of meta-associations. WIDER IMPLICATIONS: Statistically significant associations in the qualitative trend synthesis suggested that postnatal exposure to phthalates may be associated with earlier thelarche and later pubarche. However, we did not find consistent evidence in the meta-analysis for associations between timing of pubertal onset in girls and boys and exposures to any of the studied xenobiotic EDCs. We were not able to identify specific pre- or postnatal windows of exposure as particularly critical and susceptible for effects of EDCs. Current evidence is subject to several methodological challenges and inconsistencies and evidence on specific exposure-outcome associations remains too scarce to firmly confirm EDC exposure as a risk factor for changes in age of pubertal onset in the general child population. To create a more uniform foundation for future comparison of evidence and to strengthen pooled studies, we recommend the use of more standardized approaches in the choice of statistical analyses, with exposure transformations, and in the definitions and assessments of puberty outcomes. The impact of mixtures of EDC exposures on the association also remains unestablished and would be valuable to elucidate for prenatal and postnatal windows of exposure. Future large, longitudinal epidemiological studies are needed to clarify the overall association.

Prenatal exposure to maternal stressful life events and earlier age at menarche: the Raine Study.

STUDY QUESTION: Is there an association between prenatal exposure to stressful life events and age at menarche, and does childhood BMI mediate this association? SUMMARY ANSWER: Girls exposed to prenatal stress had a slightly earlier age at menarche, but this association did not show a dose-response effect and was not mediated by childhood offspring BMI. WHAT IS ALREADY KNOWN: Prenatal stress may impact on reproductive function in females including age at menarche, but human data are very limited. High childhood BMI is known to be associated with earlier age at menarche. Only one small study has measured the association between maternal stress and age at menarche and reported that childhood BMI mediated the association between maternal stress and earlier age at menarche. However, neither maternal stress nor age at menarche was prospectively recorded and the study was limited to 31 mother-daughter pairs. STUDY DESIGN, SIZE, DURATION: The Raine Study is a large prospective population-based pregnancy cohort study (n = 1414 mother-daughter pairs) continuously followed from prenatal life through to adolescence. In the present study, we examined the association between exposure to maternal stressful life events during early, late and total gestation and age at menarche in offspring using 753 mother-daughter pairs with complete case information. PARTICIPANTS/MATERIALS, SETTING, METHODS: Mothers prospectively reported stressful life events during pregnancy at 18 and 34 weeks using a standardized 10-point questionnaire. Exact date of menarche was assessed using a purpose-designed questionnaire at 8, 10, 14 and 17 years of age. Complete information on exposure, outcome and confounding variables was obtained from 753 mothers-daughter pairs. Multivariate linear regression complete case analysis was used to examine associations between maternal stressful life event exposure and age at menarche. Potential selection bias was evaluated using multiple imputations (50 datasets). The mediating effects of offspring childhood BMI (ages 5, 8, or 10 years) on these associations were measured in separate sub-analyses. MAIN RESULTS AND ROLE OF CHANCE: Most (580/753, 77%) daughters were exposed to at least one prenatal stressful life event. Exposure to maternal stressful life events during the entire pregnancy was associated with a non-linear earlier age at menarche. Exposure to one event and two or more psychological stressful events was associated with a 3.5 and 1.7-month earlier onset of puberty, respectively when compared to the reference group with no exposure maternal stressful life events. The estimates from multiple imputation with 50 datasets were comparable with complete case analysis confirming the existence of an underlying effect. No separate significant effects were observed for exposure during early or late gestation. The association between prenatal stressful events and age at menarche was not mediated by childhood BMI in the offspring. LIMITATIONS, REASONS FOR CAUTION: Stressful life events may have affected pregnant women in different ways and self-perceived maternal stress severity may have provided a more precise estimate of gestational psychological stress. The observed non-linear U-shape of the association between maternal psychological stress and age at menarche did not reflect a dose-response. This suggests that the first exposure to prenatal stress exerts a greater effect on fetal reproductive development. A potential mechanism is via dramatic initial activation of the hypothalamic-pituitary-adrenal (HPA) axis following the first stressful life event which is greater than that observed following subsequent exposure to two or more maternal stressful life events. Whilst we adjusted for a priori chosen confounders, we cannot exclude residual confounding or confounding by factors we did not include. Maternal age at menarche was not available so the effects of familial history/genetics could not be assessed. There was a large loss due to the number of girls with no information on date of menarche and missing confounder information implying risk of selection bias and multiple imputation analyses did not fully exclude this risk (similar direction but slightly weaker estimate magnitude). WIDER IMPLICATIONS OF THE FINDINGS: Menarche is a sentinel reproductive event and earlier age at menarche carries implications for psychological, social and reproductive health and for long-term risk of common non-communicable diseases. Understanding the factors regulating age at menarche has extensive health implications. This is the first population-based cohort study in humans to demonstrate that prenatal psychological stress might directly modify age at menarche. STUDY FUNDING/COMPETING INTEREST(S): Dr. Bräuner and Trine Koch's salaries were supported by Doctor Sofus Carl Emil Friis and spouse Olga Doris Friis foundation, The Danish Cancer Society (Kræftens Bekæmpelse, RP15468, R204-A12636, Denmark) and The Danish Health Foundation (Helsefonden, F-22181-23, Denmark). Martha Hickey was funded by NHMRC Practitioner Fellowships. The funding bodies played no role in the design, collection, analysis, or interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. Dr. Hart has received personal fees in his function as the Medical Director of Fertility Specialists of Western Australia and received educational sponsorship grants from MSD, Merck-Serono and from Ferring Pharmaceuticals. Dr Hart has also received personal fees from Shareholders in Western IVF outside the submitted work. TRIAL REGISTRATION NUMBER: NA.

The association between in utero exposure to maternal psychological stress and female reproductive function in adolescence: A prospective cohort study.

Background: Experimental studies suggest that prenatal stress affects reproductive function in female offspring, but human evidence is sparse and inconsistent. In this present study, we aim to investigate whether maternal psychological stress, quantified as stressful life events during pregnancy, affect reproductive function in the female offspring. Method: In a large population-based pregnancy cohort study (The Raine Study) continuously followed from prenatal life through to adolescence we examined the association between the number of maternal stressful life events in both early and late gestation and subsequent ovarian and uterine function in 228 female adolescent offspring. Mothers prospectively reported stressful life events during pregnancy at 18 and 34 weeks using a standardized 10-point questionnaire. Female offspring (n â€‹= â€‹228) age 14-16 years underwent gynecological examination including transabdominal abdominal ultrasound (TAUS) to measure uterine volume and ovarian AFC. Plasma samples on day 2-6 of the spontaneous menstrual cycle measured circulating AMH and inhibin B. Multivariate linear regression analysis was used to examine the associations between maternal stressful life events and reproductive function in female offspring. Adolescents taking hormonal contraception were excluded. Results: Most adolescents (145/228, 64%) were exposed to at least one stressful life event in early gestation and around half (125/228, 55%) were exposed to at least one in later gestation. Exposure to one or more maternal stressful life events in late gestation was associated with a greater uterine volume (ߠ​= â€‹0.13, 95% CI 0.04; 0.23) and higher ovarian AFC (ߠ​= â€‹0.19, 95% CI 0.02; 0.35) at age 14-16 years. No associations between maternal stressful events in late gestation and reproductive function were identified. No associations between stressful life events in early or late gestation and circulating AMH or Inhibin B were observed. Conclusion: Maternal psychological stress in late, but not early gestation was associated with a significantly greater uterine volume and ovarian antral follicle count (AFC) in adolescent offspring but did not affect ovarian production of antimullerian hormone (AMH) or Inhibin B. These findings suggest that female reproductive function is influenced by prenatal exposure to stress.

In utero exposure to maternal stressful life events and risk of polycystic ovary syndrome in the offspring: The Raine Study.

BACKGROUND: PCOS is the most common endocrine disorder in reproductive age women. The origins of PCOS are unknown but experimental and limited human evidence suggests that greater prenatal exposure to androgens may predispose to PCOS. Experimental evidence suggests that maternal stressors may affect reproductive function in the offspring via changes in prenatal androgen exposure. In this present study, we aim to investigate whether maternal stressful life events during pregnancy are associated with polycystic ovary morphology (PCOM) or polycystic ovary syndrome (PCOS) in adolescent offspring. METHOD: In a large population-based pregnancy cohort study (The Raine Study) continuously followed from prenatal life through to adolescence we examined the association between maternal stressful life events during pregnancy in both early and late gestation, and subsequent circulating concentrations of ovarian and adrenal androgens, PCOM and PCOS in the normal menstrual cycle of offspring age 14-16 years. Maternal stressful life events were prospectively recorded during pregnancy at 18 and 34 weeks using a 10-point questionnaire. Female offspring (n = 223) completed a questionnaire about their menstrual cycles, underwent a clinical examination for hirsutism (Ferriman-Gallwey score) and transabdominal pelvic ultrasound examination to determine ovarian morphology according to standardized criteria for classification of PCOM. Plasma samples were obtained at day 2-6 of the normal menstrual cycle for measurement of androgens. PCOM was defined according to the international consensus definition, 2003 and the evidence-based guideline for the assessment and management of PCOS, 2018. PCOS was diagnosed according to Rotterdam criteria and National Institute of Health (NIH) criteria. Multivariate linear and logistic regression analyses were used to examine the associations between maternal stressful life event exposure and ovarian morphology (PCOM), circulating ovarian and adrenal androgens (clinical and biochemical hyperandrogenism (hirsutism)) and presence of PCOS. RESULTS: Of 223 recruited adolescent girls, 78 (35.9%) and 68 (31.3%) had PCOM by the 2003 and 2018 criteria respectively, while 66 (29.6%) and 37 (16.6%) had PCOS, using Rotterdam and NIH criteria, respectively. Most girls (141/223, 63.2%) were exposed to at least one stressful life event in early gestation and around half (121/223, 54.3%) were exposed to at least one stressful life event in late gestation. Maternal stressful life events in early gestation were associated with a statistically significant lower prevalence of PCOM when applying the 2003 criteria [adjusted odds ratio [aOR] and 95% confidence intervals (CI): 0.74 (95% CI: 0.55; 0.99)], and a similar association was detected when applying the 2018 PCOM criteria (aOR, 0.69, 95% CI: 0.50; 0.95)]. Maternal stressful life events in early gestation were also associated with lower circulating concentrations of testosterone (ß = -0.05, 95% CI: -0.09; -0.004) and androstenedione (ß = -0.05, 95% CI: -0.10; -0.002) in the offspring. No similar effects for PCOM or circulating androgens were detected in late gestation. No statistically significant associations between maternal stressful life events in early or late gestation with PCOS (neither Rotterdam nor NIH criteria) in adolescence were detected. The prospective collection of maternal stressful life events during both early and late gestation and direct measurement of PCOM, PCOS and circulating androgens in adolescence and key co-variates implies minimal possibility of recall, information bias and selection bias. CONCLUSION: Maternal exposure to stressful life events in early gestation is associated with significantly reduced circulating ovarian and adrenal androgen concentrations in adolescence (testosterone and androstenedione), and an indication of fewer cases of polycystic ovary morphology (PCOM) defined by the 2003 international consensus definition and by the 2018 international evidence-based guideline, but has no effect on polycystic ovary syndrome (PCOS), diagnosed using either Rotterdam or NIH criteria.

The association between in-utero exposure to stressful life events during pregnancy and male reproductive function in a cohort of 20-year-old offspring: The Raine Study.

STUDY QUESTION: Is exposure to gestational stress in the critical time window for the normal differentiation and growth of male reproductive tissue associated with male reproductive function in offspring in later life? SUMMARY ANSWER: Exposure to stressful life events (SLEs) in early, but not late gestation, are associated with reduced adult male reproductive function, consistent with the hypothesis that events during early prenatal life programme adult male reproductive function. WHAT IS ALREADY KNOWN: Animal studies suggest that gestational stress may impact on the reproductive function of male offspring, but human evidence is sparse. STUDY DESIGN, SIZE, DURATION: Using a prospective longitudinal cohort, we examined the association between number and type of maternal stressors during pregnancy in both early and late gestation and reproductive function in 643 male Generation 2 (offspring) at age 20 years. Mothers and their male Generation 2 (offspring) from The Raine Study participated. Mothers prospectively reported SLEs during pregnancy recorded at gestational weeks 18 and 34 using a standardized 10-point questionnaire. PARTICIPANTS/MATERIALS, SETTING, METHODS: The 643 male Generation 2 (offspring) underwent testicular ultrasound examination and semen analysis and provided serum for reproductive hormone analysis. Multivariate linear regression analysis was used to examine associations. MAIN RESULTS AND ROLE OF CHANCE: Of 643 recruited males, 407 (63%) were exposed to at least one SLE in early gestation. Fewer SLEs were reported in late gestation (n = 343, 53%). Maternal SLE exposure in early gestation was negatively associated with total sperm count (ß = -0.31, 95% CI -0.58; -0.03), number of progressive motile sperm (ß = -0.15, 95% CI -0.31; 0.00) and morning serum testosterone concentration (ß = -0.04, 95% CI -0.09; -0.00). No similar effects of maternal SLE exposure in late pregnancy were detected. The large sample size and an objective detailed direct assessment of adult male reproductive function with strict external quality control for sperm quality, as well as detailed prospectively collected information on prenatal SLEs in two distinct time windows of pregnancy reported by the women in early and late gestation along with other risk factors, imply minimal possibility of recall, information bias and selection bias. When assessing our results, we adjusted for a priori chosen confounders, but residual confounding or confounding by factors unbeknown to us cannot be ruled out. LIMITATIONS, REASONS FOR CAUTION: It is not possible to measure how SLEs impacted differently on the mother's experience or perception of stress. Resilience (coping) gradients may alter cortisol levels and thus modify the associations we observed and the mothers' own perception of stress severity may have provided a more precise estimate of her exposure. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that exposure to SLEs in early, but not late gestation, are associated with reduced adult male reproductive function. Improved support for women with exposure to SLEs during pregnancy, particularly during the first trimester, may improve the reproductive health of their male offspring in later life. Intervention studies of improved pregnancy support could provide more insight into this association and more information is needed about the potential specific epigenetic mechanisms underlying this association. STUDY FUNDING/COMPETING INTEREST(S): The male fertility sub-study was funded by NHMRC Grant 634 457. The core management of the Raine Study is funded by University of Western Australia, Curtin University, Telethon Kids Institute, Women and Infants Research Foundation, Edith Cowan University, Murdoch University, The University of Notre Dame Australia and Raine Medical Research foundation. Dr Bräuner's salary was supported by Læge Sofus Carl Emil Friis og Hustru Olga Doris Friis foundation in Denmark. All authors declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Variation in residential radon levels in new Danish homes.

Radon-222 gas arises from the radioactive decay of radium-226 and has a half-life of 3.8 days. This gas percolates up through soil into buildings, and if it is not evacuated, there can be much higher exposure levels indoors than outdoors, which is where human exposure occurs. Radon exposure is classified as a human carcinogen, and new Danish homes must be constructed to ensure indoor radon levels below 100 Bq/m(3). Our purpose was to assess how well 200 newly constructed single detached homes perform according to building regulations pertaining to radon and identify the association between indoor radon in these homes and municipality, home age, floor area, floor level, basement, and outer wall and roof construction. Median (5-95 percentile) indoor radon levels were 36.8 (9.0-118) Bq/m(3) , but indoor radon exceeded 100 Bq/m(3) in 14 of these new homes. The investigated variables explained nine percent of the variation in indoor radon levels, and although associations were positive, none of these were statistically significant. In this study, radon levels were generally low, but we found that 14 (7%) of the 200 new homes had indoor radon levels over 100 Bq/m(3). More work is needed to determine the determinants of indoor radon.

Effects of a 17q21 chromosome gene variant, tobacco smoke and furred pets on infant wheeze.

The first common genetic factor identified for pediatric asthma by genome-wide association is the chromosome 17q21 locus, harbouring the ORMDL3 gene. ORMDL3 is involved in facilitation of endoplasmic reticulum-mediated inflammatory responses, believed to underlie its asthma association. We investigated associations between the rs7216389 polymorphism in the 17q21 locus affecting ORMDL3 expression and the risk for recurrent wheeze and interactions with exposure to tobacco smoke and furred pets during pregnancy and infancy using a birth cohort of 101,042 infants. Rs7216389 was significantly associated with recurrent wheeze risk among 18-month-old infants. There was a 1.35-fold higher risk of recurrent wheeze among homozygous variant allele carriers compared with homozygous wild-type allele carriers. There was significant interaction between rs7216389 and domestic furred pets, with a positive association between pets and wheeze among homozygous wild-type carriers and a negative association among homozygous variant allele carriers. There was no interaction between rs7216389 and tobacco smoke exposure.