Objective To investigate the association of urinary bisphenol A (BPA) concentration during different pregnancy stages with overweight/obesity in children aged 2 years based on a birth cohort.

Methods A total of 626 women with a singleton pregnancy and their infants who were recruited in Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital) from October 2013 to October 2015 were enrolled as subjects, and their related information was collected, including urine samples in the three trimesters and delivery information. The infants were followed up to 2 years old to obtain the data on physical growth. Ultra-high-performance liquid chromatography-triple quadrupole mass spectrometry was used to measure the urinary concentration of BPA, and the multivariate logistic regression model was used to analyze the association of BPA exposure during different pregnancy stages with overweight/obesity in children aged 2 years.

Results The median (P₂₅, P₇₅) mass concentrations of BPA in the urine samples of the first, second, and third trimesters were 1.37 (0.11, 4.00) ng/mL, 1.39 (0.16, 3.76) ng/mL, and 1.22 (0.20, 3.62) ng/mL, respectively. Among the 626 children, 134 (21.41%) were overweight/obesity at the age of 2 years. After adjustment for potential confounding factors, the logistic regression analysis showed that BPA exposure in the third trimester was positively associated with overweight/obesity in children aged 2 years (Q4 group: OR=2.11, 95%CI: 1.15-3.85). Stratified analysis based on gender showed that this association was found only in girls (Q3 group: OR=5.21, 95%CI: 1.52-17.85; Q4 group: OR=6.12, 95%CI: 1.81-20.74).

Conclusion BPA exposure in the third trimester is positively associated with overweight/obesity in girls aged 2 years. Pregnant women should avoid BPA exposure during pregnancy, especially in the third trimester.