Polybrominated diphenyl ethers in early pregnancy and preterm birth: Findings from the NICHD Fetal Growth Studies.

BACKGROUND

Studies suggest associations between exposure to individual polybrominated diphenyl ethers (PBDEs) with preterm birth (PTB) and shorter gestational age. Little is known about exposure to PBDE mixtures and these outcomes. We evaluated associations of multiple PBDEs in early pregnancy with gestational age at delivery and PTB.

METHODS

Data were collected from 2046 women without obesity and 396 women with obesity from the NICHD Fetal Growth Studies, who had early pregnancy plasma PBDEs concentrations and gestational age at delivery. PTB was defined as < 37 weeks of gestation at delivery and further categorized into subtypes (late or very early/moderate; spontaneous or medically indicated). We applied (1) generalized linear models (GLM); (2) principal component analysis (PCA); and (3) Bayesian Kernel Machine Regression (BKMR) to evaluate the individual and joint associations of log-transformed PBDE concentrations with gestational age at delivery and PTB, adjusting for potential confounders and evaluating effect modifiers.

RESULTS

In GLM analyses, a 1-standard deviation (SD) increase in log-PBDE 153 was associated with shorter gestational age at delivery [adjusted β (95% CI) = -0.19 (-0.31, -0.06) weeks] among women without obesity. In PCA analyses, 1-SD increase in the principal component summarizing most of PBDE 153 variability was associated with shorter gestational age at delivery [adjusted β (95% CI) = -0.18 (-0.30, -0.06) weeks], very early/moderate PTB [adjusted OR (95% CI) = 1.91 (1.19, 3.07)], and spontaneous PTB [adjusted OR (95% CI) = 1.34 (1.00, 1.80)] among women without obesity. Associations were stronger among non-Hispanic Black women, women with BMI ranging between 25 and 30 kg/m, and women who were ≥35 years old among those without obesity. In BKMR analyses, a suggestive inverse association between PBDE 153 and gestational age at delivery, and an inverse U-shaped association between PBDE 154 and gestational age at delivery were observed in women without obesity. No statistically significant association of PBDEs and gestational age or PTB was observed among women with obesity.

CONCLUSIONS

PBDEs, specifically PBDE 153, were associated with shorter gestation and higher risk of certain PTB subtypes among pregnant women without obesity.