Trimester-specific, gender-specific, and low-dose effects associated with non-monotonic relationships of bisphenol A on estrone, 17β-estradiol and estriol

•Non-monotonic relationships between BPA and estrogen were noted among mothers.•Gender-specific associations of BPA with estrogen were observed.•Trimester-specific associations between BPA and estrogen were observed.•BPA was non-linearly associated with estrogen even under the safety threshold. Bisphenol A (BPA) may cause some adverse effects on human health by mimicking estrogen activities. In vitro andanimalstudies have observed the non-monotonic associations between BPA and natural estrogens, but the evidence in human study is lacking, particularly at multiple points in time during pregnancy. We aimed to examine the relationships between BPA and estrogens in the three trimesters among Chinese pregnant women and their gender variations. This study included 851 participants from a birth cohort conducted in Wuhan, China between 2014 and 2015. We measured concentrations of BPA and three estrogens (estrone (E1), 17β-estradiol (E2) and estriol (E3)) in urine samples collected in the three trimesters of pregnancy (mean for each visit: 13.0, 23.6, and 35.9 weeks’ gestation). We calculated the estimated daily intakes using urinary BPA concentrations and compared them with the tolerable intake value to assess potential health risks. We used multivariate linear regression models stratified by trimester and gender to explore trimester-specific and gender-specific associations of BPA with E1, E2, and E3. We found the decreased levels of estrogens (β