High BPA, paraben concentrations during pregnancy linked to preterm delivery

Exposure to parabens and bisphenol A (BPA) during early and mid-to-late pregnancy, respectively, may contribute to an increased risk of preterm birth among women carrying female infants, a study has found.

The study included 386 mothers (mean age 34.7 years, mean body mass index 24.2 kg/m²) who sought fertility treatment and gave birth to a singleton. The mean gestational age of the infants was 39.4 weeks, with 31 (8 percent) born preterm (gestational age <37 weeks). In terms of birth weight, the mean was 3,352 grams, with 16 infants (4 percent) born with low birth weight (<2,500 grams).

Compared with women who delivered at term, those who did preterm had higher urinary BPA concentrations, specifically during mid-to-late pregnancy and among those with female infants. Multivariable logistic regression confirmed that second trimester BPA concentrations were tied to preterm birth (risk ratio [RR], 1.24, 95 percent confidence interval [CI], 0.92–1.69), and this association was primarily driven by female (RR, 1.40, 95 percent CI, 1.04–1.89) but not male (RR, 0.85, 95 percent CI, 0.50–1.46) infants.

First trimester paraben concentrations also showed an association with preterm birth (RR, 1.17, 95 percent CI, 0.94–1.46), and this was likewise limited to female infants (RR, 1.46, 95 percent CI, 1.10–1.94).

There was a trend of association between first trimester urinary bisphenol S concentrations and preterm birth (RR, 1.25, 95 percent CI, 0.82–1.89), but the numbers were small and precluded sex-specific examination.

Despite the findings, the study did not identify a unique critical window of risk for preterm birth in relation to BPA exposure. More studies are needed.