Urinary Bisphenol A Levels during Pregnancy and Risk of Preterm Birth.

Background: Preterm birth (PTB), a leading cause of infant mortality and morbidity, has a complex etiology with a multitude of interacting causes and risk factors. The role of environmental contaminants, particularly bisphenol A (BPA), is understudied with regard to PTB. Objectives: In the present study we examined the relationship between longitudinally measured BPA exposure during gestation and PTB. Methods: A nested case–control study was performed from women enrolled in a prospective birth cohort study at Brigham and Women's Hospital in Boston, Massachusetts, during 2006-2008. Urine samples were analyzed for BPA concentrations at a minimum of three time points during pregnancy on 130 cases of PTB and 352 randomly assigned controls. Clinical classifications of PTB were defined as “spontaneous,” which was preceded by spontaneous preterm labor or preterm premature rupture of membranes, or “placental,” which was preceded by preeclampsia or intrauterine growth restriction. Results: Geometric mean concentrations of BPA did not differ significantly between cases and controls. In adjusted models, urinary BPA averaged across pregnancy was not significantly associated with PTB. When examining clinical classifications of PTB, urinary BPA late in pregnancy was significantly associated with increased odds of delivering a spontaneous PTB. After stratification on infant's sex, averaged BPA exposure during pregnancy was associated with significantly increased odds of being delivered preterm among females, but not males. Conclusions: These results provide little evidence of a relationship between BPA and prematurity, though further research may be warranted given the generalizability of participant recruitment from a tertiary teaching hospital, limited sample size, and significant associations among females and within the clinical subcategories of PTB. [ABSTRACT FROM AUTHOR]