Associations between antenatal organophosphate pesticide exposure and pregnancy outcomes: The Japan Environment and Children's Study (JECS)

To examine the association between antenatal exposure to organophosphate (OP) pesticides, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, and pregnancy outcomes in Japan's large nationwide birth cohort. We included 4444 pregnant women from the Japan Environment and Children's Study (JECS). Urinary concentrations of six DAP metabolites during the first trimester were measured. Multiple linear and logistic regression analyses were performed to examine the associations of DAP metabolites with gestational age at birth, birth weight, preterm birth (PTB), low birth weight (LBW), and small-for-gestational-age (SGA), adjusting for potential confounders. Non-linear associations were found between higher dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) concentrations and the lower risk of PTB. A 10-fold increase in DMP and diethylphosphate (DEP) concentrations was associated with larger gestational weeks at birth: adjusted β = 0.13 (95 %CI, 0.02-0.23) and 0.14 (95 %CI, 0.03-0.25), respectively. Higher DMP concentration was associated with a lower risk of LBW. These associations were not significant after applying the Bonferroni correction. The associations between DAP metabolites and gestational week were more evident among mothers who delivered male infants, mothers with higher education, higher household income, and higher fruit consumption. No metabolites showed associations with birth weight. Exposure to higher concentrations of OPs, measured by urinary DAP metabolites, had no robust association with gestational age at birth or birth weight. Further studies are warranted to investigate the effect of OP exposure on pregnancy outcomes.