Association of BPA exposure during pregnancy with risk of preterm birth and changes in gestational age: A meta-analysis and systematic review.

The associations of bisphenol A exposure during pregnancy with risk of preterm birth (PTB) and changes in gestational age have remained controversial. To conduct the meta-analysis, the relevant studies were searched through PubMed, OVID, and Web of Science from inception through June ‎17, ‎2020. Data were independently extracted and analyzed using odds ratio (OR) or regression coefficient (β) and their 95% confidence intervals (CIs). We identified 668 references and included 7 studies for preterm birth and 9 studies for gestational age. The included studies reported that the median or geometric mean (GM) of maternal urinary BPA ranged from 0.48 to 6.44 ng/ml. The meta-analysis estimated OR to be 1.36 (95% CI: 1.03, 1.69) for preterm birth associated with maternal urinary BPA exposure during pregnancy. In the subgroup analysis based on BPA exposure level, a significant association was observed between preterm birth and higher BPA exposure among the populations had BPA median or GM concentrations higher than 2.16 ng/ml (OR: 1.92; 95% CI: 1.38, 2.47). In the subgroup analyses by maternal urinary BPA exposure assessed in different trimesters, a significant association of preterm birth was only observed with BPA assessed in the third trimester (OR: 1.62; 95% CI: 1.15, 2.09). In addition, higher maternal urinary BPA exposure during pregnancy was associated with decreased gestational age by 0.50 (-0.87, -0.13) days, and the subgroup analyses also showed that only BPA exposure in the third trimester was associated with decreased gestational age by 1.36 (-2.21, -0.52) days. This meta-analysis demonstrated that higher BPA exposure was associated with an increased risk of preterm birth and decreased length of gestational age, and suggested that BPA exposure in the third trimester of pregnancy may be a critical susceptible period of preterm birth.