Prenatal organophosphate flame retardant exposure and the odds of small- and large-for-gestational age births

Abstract

Background: Deviations in normal fetal growth trajectories may predispose infants to adverse outcomes later in life, such as cardio-metabolic disorders and decreased intellectual performance during childhood. Environmental exposures, including commonly used organophosphate flame retardants (OPFRs), have the ability to disturb normal hormonal and metabolic processes during pregnancy; however, associations with fetal growth have been minimally examined in human populations. Methods: Using a pilot case-control study, we investigated the association between 9 OPFRs and the odds of small-for (SGA) and large-for-gestational age (LGA) births. Concentrations of OPFRs were measured in maternal urine collected from three study visits during pregnancy using high performance liquid chromatography-tandem mass spectrometry. SGA (<10th percentile birth weight-for-gestational age, n = 30), LGA (>90th percentile, n = 30), and control (10th - 90th percentile, n = 30) births were selected from the LIFECODES birth cohort study. Odds ratios (OR) and 95% confidence intervals (95% CI) for associations between average OPFR concentrations over pregnancy and SGA and LGA were estimated using multinomial logistic regression. Results: Among the 9 urinary OPFRs measured, only bis(1,3-dichloro-2-propyl) phosphate (BDCPP) and diphenyl phosphate (DPHP) were detected in at least 85% of the participants at each study visit. After adjusting for potential confounders, we observed inverse associations between BDCPP and DPHP concentrations and odds of delivering an LGA baby. For example, a log-unit increase in BDCPP was associated with an OR (95% CI) of 0.37 (0.16, 0.84). All associations between OPFR concentrations and SGA were null. Conclusions: In a pilot study of prenatal OPFR exposure and fetal growth, urinary OPFR concentrations were associated with reduced odds of delivering LGA. While no associations with the SGA group were observed, these findings are consistent with previous observations that OPFRs are associated with lower measures of fetal growth and warrant additional investigation in future work.