Organophosphate ester flame retardant chemicals and maternal depression during pregnancy

Depression substantially contributes to pregnancy-related morbidity, and pregnancy is increasingly recognized as a vulnerable window for exposure effects on maternal mental health. Exposures to organophosphate esters (OPEs) are ubiquitous and may have neurotoxic effects; however, their impacts on prenatal depression remain unknown. We evaluated associations of third trimester OPE metabolites on maternal depressive symptoms during pregnancy.

This study included 422 participants in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) cohort, a prospective pregnancy cohort of primarily low-income and Hispanic participants residing in Los Angeles, California. We measured concentrations of nine OPEs in third trimester spot urine samples (mean gestational age = 31.5 ± 2.0 weeks). Using the Center for Epidemiologic Studies-Depression (CES-D) scale, we classified participants as having probable depression during pregnancy (N = 137) or not (N = 285) if one or more CES-D scores administered at each trimester met the suggested cutoff score for clinically significant depressive symptoms (≥16). We estimated associations of prenatal OPE metabolite concentrations in tertiles and risk of prenatal depression using modified Log-Poisson regression. We examined associations of the OPE mixture on depression during pregnancy using Bayesian kernel machine regression (BKMR).

Participants with the highest tertiles of DPHP and BDCIPP exposure had a 67% (95% CI: 22%, 128%) and 47% (95% CI: 4%, 108%) increased risk of maternal depressive symptoms during pregnancy, respectively. No associations between other OPE metabolites and maternal depression symptoms were observed. In mixture analyses, we observed a positive and linear association between higher exposure to the OPE metabolite mixture and odds of prenatal maternal depression, primarily driven by DPHP.

Our findings provide new evidence of associations between frequently detected OPE metabolites on maternal depression symptoms during pregnancy. Results could inform future intervention efforts aimed at reducing perinatal maternal depression.