Maternal bisphenol and phthalate urine concentrations and weight gain during pregnancy

Background: Insufficient or excessive gestational weight gain are associated with increased risks of adverse birth and childhood outcomes. Increasing evidence suggests that exposure to bisphenols and phthalates may disrupt hormonal pathways and thereby influence gestational weight gain. Objective: To examine the associations of early and mid-pregnancy bisphenol and phthalate urine concentrations with gestational weight gain. Methods: In a population-based prospective cohort study among 1,213 pregnant women, we measured early and mid-pregnancy bisphenol and phthalate urine concentrations. Maternal anthropometrics before pregnancy were obtained by questionnaire and repeatedly measured at our research center during pregnancy. We used linear and logistic regressions to evaluate the associations of bisphenols and phthalates with total and period-specific gestational weight gain. Results: Higher maternal total bisphenols and bisphenol S were associated with a lower total gestational weight gain at nominal level. Stratification by body mass index group showed that higher total bisphenols and bisphenol S were associated with lower total gestational weight gain specifically in normal weight women (respectively −509 g [95% CI −819, −198] and −398 g [95% CI −627, −169]). Each log unit increase in early pregnancy total bisphenol and bisphenol A urine concentrations were associated with lower mid- to late pregnancy gestational weight gain in the whole group (effect estimates −218 g/log unit increase [95% CI −334, −102] and −132 g/log unit increase [95% CI −231, −34], respectively). These associations were independent of mid-pregnancy compounds. Mid-pregnancy bisphenols and phthalates concentrations were not associated with gestational weight gain. Discussion: Higher maternal bisphenol urine concentrations in early pregnancy may lead to reduced gestational weight in second half of pregnancy. Further research is needed to assess the effects of maternal bisphenols and phthalates urine concentrations on placental and fetal growth and development. Keywords: Bisphenol, Phthalate, Gestational weight gain, Cohort studies