Maternal urinary organophosphate ester concentrations and blood pressure during pregnancy: The HOME Study

Abstract

BACKGROUND AND AIM: Organophosphate esters (OPEs) flame retardants found in various consumer products, may be a risk factor of adverse reproductive health outcomes. No study has examined whether gestational exposure to OPEs alters maternal blood pressure (BP) during pregnancy. METHODS: We analyzed data from 346 women who had liveborn singletons without congenital abnormalities in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective birth cohort (Cincinnati, OH, USA). The exposure variables were maternal urinary OPE metabolite concentrations at 16 weeks of gestation, standardized by specific gravity. We extracted the first two recorded maternal BP measures (20 weeks) to assess for chronic hypertension. We also extracted the two highest BP measures (≥20 weeks), and any diagnosis of hypertensive disorders of pregnancy (HDP: gestational hypertension, preeclampsia, and eclampsia) from medical charts. We defined HDP for this analysis as two BP140/90 or HDP noted in the chart at or after 20 weeks gestation. We used linear mixed models and modified Poisson regression with covariate adjustment to estimate associations between OPE concentrations with maternal BP and the risk of HDP. RESULTS:Diphenyl phosphate (DPHP) had the highest urinary geometric mean concentration (1.81 µg/L), followed by bis(1,3-dichloro-2-propyl) phosphate (BDCIPP; 0.80 µg/L), bis(2-chloroethyl) phosphate (BCEP; 0.61 µg/L), and di-n-butyl phosphate (DNBP; 0.26 µg/L). Thirty women (8.7%) were diagnosed with HDP. Every 10-fold increase of maternal BCEP concentrations was associated with 1.87 mmHg (95%CI 0.05-3.70) increase in the highest diastolic BP≥20 weeks. No urinary metabolites were associated with an increased risk of HDP (RR=1.17, 95%CI: 0.55-2.50 for DPHP; RR=1.68, 95%CI: 0.62-4.58 for BDCIPP; RR= 0.75, 95%CI 0.37-1.53 for BCEP; RR=2.34, 95% CI:0.88-6.24 for DNBP). CONCLUSIONS:Maternal urinary BCEP concentrations may be associated with increased diastolic BP. However, no associations were found between maternal urinary OPE metabolites and an increased risk of HDP. KEYWORDS: Endocrine disrupting chemicals, Pregnancy outcomes, Environmental epidemiology