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Background: In experimental studies, several polycyclic aromatic hydrocarbons (PAHs) have shown endocrine disrupting properties, but very few epidemiological studies have examined their impact on pubertal development and results have been heterogenous. Objective: To explore if maternal PAH exposure during pregnancy was associated with the offspring's timing of pubertal onset. Methods: We studied 582 mother-daughter dyads originating from a population-based cohort in a rural setting in Bangladesh. Maternal urinary samples, collected in early pregnancy (on average, gestational week 8), were analyzed for monohydroxylated metabolites of phenanthrene (1-OH-Phe, E2-,3-OH-Phe, and 4-OH-Phe), fluorene (E2-,3-OH-Flu), and pyrene (1-OH-Pyr) using liquid chromatography with tandem mass spectrometry (LCMS/MS). The girls were interviewed on two separate occasions concerning date of menarche, as well as breast and pubic hair development according to Tanner. Associations were assessed using Kaplan-Meier analysis and multivariable-adjusted Cox proportional hazards regression or ordered logistic regression. Results: In early pregnancy, the mothers' median urinary concentrations of E1-,2-,3-,4-OH-Phe, E2-,3-OH-Flu, and 1-OH-Pyr were 3.25 ng/mL, 2.0 ng/mL, and 2.3 ng/mL respectively. At the second follow-up, 78 % of the girls had reached menarche, and the median age of menarche was 12.7 +/- 0.81 years. Girls whose mothers belonged to the second and third quintiles of EOH-Phe metabolites had a higher rate of menarche, indicating a younger menarcheal age (HR 1.39; 95 % CI 1.04, 1.86, and HR 1.41; 95 % CI 1.05, 1.88, respectively), than girls of mothers in the lowest quintile. This trend was not observed in relation to either breast or pubic hair development. None of the other maternal urinary PAH metabolites or the sum of all thereof in early pregnancy were associated with age at menarche or pubertal stage. Conclusions: Indications of non-monotonic associations of prenatal phenanthrene

Introduction: A history of preterm birth reportedly increases the risk of subsequent preterm birth. This association has primarily been studied in high-income countries and not in low-income settings in transition with rapidly descending preterm birth figures. We evaluated the population-based trends of preterm births and recurrent preterm births and the risk of preterm birth recurrence in the second pregnancy based on prospectively studied pregnancy cohorts over three decades in Matlab, Bangladesh. Methods: A population-based cohort included 72 160 live births from 1990 to 2019. We calculated preterm birth and recurrent preterm birth trends. We assessed the odds of preterm birth recurrence based on a subsample of 14 567 women with live-born singletons in their first and second pregnancies. We used logistic regression and presented the associations by OR with a 95% CI. Results: The proportion of preterm births decreased from 25% in 1990 to 13% in 2019. The recurrent preterm births had a similar, falling pattern from 7.4% to 3.1% across the same period, contributing 27% of the total number of preterm births in the population. The odds of second pregnancy preterm birth were doubled (OR 2.18; 95% CI 1.96 to 2.43) in women with preterm birth compared with the women with term birth in their first pregnancies, remaining similar over the study period. The lower the gestational age at the first birth, the higher the odds of preterm birth in the subsequent pregnancy (test for trend p<0.001). Conclusion: In this rural Bangladeshi setting, recurrent preterm births contributed a sizeable proportion of the total number of preterm births at the population level. The increased risk of recurrence remained similar across three decades when the total proportion of preterm births was reduced from 25% to 13%.

BACKGROUND: Several metals act as endocrine disruptors, but there are few large longitudinal studies about associations with puberty onset.OBJECTIVES: We evaluated whether early life cadmium, lead, and arsenic exposure was associated with timing of menarche. METHODS: In a mother-child cohort in rural Bangladesh (n = 935), the exposure was assessed by concentrations in maternal erythrocytes in early pregnancy and in girls' urine at 5 and 10 years of age using inductively coupled plasma mass spectrometry. The girls were interviewed twice, at aver-age ages 13.3 [standard deviation eth SD THORN = 0.43] and 13.8 (SD = 0.43) y, and the date of menarche, if present, was recorded. Associations were assessed using Kaplan-Meier analysis and multivariable-adjusted Cox regression.RESULTS: In total, 77% of the girls (n = 717) had reached menarche by the second follow-up. The median age of menarche among all girls was 13.0 y (25th-75th percentiles: 12.4-13.7 y). At 10 years of age, median urinary cadmium was 0.25 mu g/L (5th-95th percentiles: 0.087-0.72 mu g/L), lead 1.6 mu g/L (0.70-4.2 mu g/L), and arsenic 54 mu g/L (19-395 mu g/L). Given the same age, girls in the highest quartile of urinary cadmium at 5 and 10 years of age had a lower rate of menarche than girls in the lowest quartile, with an adjusted hazard ratio of (HR) 0.80 (95% CI: 0.62, 1.01) at 5 years of age, and 0.77 (95% CI: 0.60, 0.98) at 10 years of age. This implies that girls in the highest cadmium exposure quartile during childhood had a higher age at menarche. Comparing girls in the highest to the lowest quartile of urinary lead at 10 years of age, the former had a higher rate of menarche [adjusted HR = 1.23 (95% CI: 0.97, 1.56)], implying lower age at menarche, whereas there was no association with urinary lead at 5 years of age. Girls born to mothers in the highest quartile of erythrocyte arsenic during pregnancy were less likely to have attained menarche than girls born to mothers in the low-est quartile [a