Pregnancy exposure to environmental phenols and breastfeeding duration in the HOME Study

Environmental phenols are endocrine-disrupting chemicals widely used in personal care products. They have been shown to affect the mammary gland, but knowledge about their impact on breastfeeding duration is limited. We aimed to explore associations between maternal phenols exposure during pregnancy and breastfeeding duration. We included 373 mother-infant pairs from the Health Outcomes and Measures of the Environment (HOME) Study (Cincinnati, Ohio, USA) enrolled from 2003 to 2006. We measured urinary concentrations of eight phenols at 16 and 26 weeks of gestation (bisphenol A, triclosan, benzophenone-3, 2,4-/2,5-dichlorophenols, methyl-/propyl-/butyl-paraben) and collected breastfeeding information until mothers reported discontinuation of exclusive and any breastfeeding. We assessed the hazard ratios (HRs) and odds ratios (ORs) of the cessation of breastfeeding in relation to the eight phenols using confounder adjusted Cox proportional hazards and logistic regression models, respectively. In adjusted Cox regression models, each doubling of urinary triclosan concentration was associated with HRs of 1.09 (95% CI: 1.00, 1.18) for any breastfeeding cessation within 6 months, and 1.08 (95% CI: 0.96, 1.21) for cessation between 6 and 12 months, with tertile-categorized analyses suggesting a dose-response relationship for cessation within 6 months. We did not observe consistent associations with breastfeeding duration for the seven other phenols, but each doubling concentrations in triclosan and BP-3 were associated with 18% (95% CI: 3, 35%) and 13% (95% CI: 1, 26%), respectively, higher odds of terminating breastfeeding earlier than intended. Considering the limited sample size and multiple testing, our findings need to be confirmed in larger studies.