Urinary organophosphate metabolite concentrations and birth sizes among women conceiving through in vitro fertilization in Shanghai, China

Background: Few studies have examined the adverse birth sizes of preconception exposure to organophosphate pesticides (OPs) in women undergoing in vitro fertilization (IVF).Objectives: We investigated the relationship of preconception OP exposure with birth sizes among Chinese women undergoing IVF.Methods: This study included 302 couples seeking infertility treatment in the China National Birth Cohort Study, from Shanghai, China, who gave birth to singleton infants between 2018 and 2021. Clinical data were collected from medical records. We measured the concentrations of six nonspecific dialkyl phosphates (DAP) metabolites of OPs [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethyldithiophosphate (DMTP), dimethylphosphate (DMP), and dimethyldithiophosphate (DMDTP)] in maternal urine. DMDTP and DEDTP were precluded from further analyses due to the low detection rates. Generalized linear models (GLMs) and weighted quantile sum (WQS) regression analyses were performed to examine the individual and joint effects of OP exposures on gestational age, birth weight, body length, and ponderal index. Odder ratio (OR) of preterm birth were estimated using logistic regression models. Results: Women in the highest as compared with lowest quartile of DEP had shorter gestational age (13 = -0.68; 95% CI =-1.24,-0.11). The association was modified by sex, with boys showing larger decreases in gestational age (13 = -0.86; 95% CI =-1.60,-0.13). No associations were found between other DAP metabolites and birth sizes. Results from linear models with individual DAP metabolites were corroborated by the WQS regression where DEP had the largest contribution to the overall mixture effect on gestational age (weight = 0.70). Moreover, DEP concentration was associated with an elevated risk of preterm birth (OR = 1.35, 95% CI = 1.11, 2.25).Conclusion: Preconception DEP concentration was associated with shortened gestational age and increased risk of preterm birth, and the association was more pronounced among boys than girls.