Exposure Characteristics of Phthalate Metabolites Among The Zunyi Cohort of Pregnant Women in Southwest China

Abstract Reported evidence has increasingly indicated that exposure to phthalates can cause adverse pregnancy outcomes. However, phthalate exposure levels among pregnant women remains unclear. We aimed to evaluate the concentrations of phthalate metabolites in urine samples of the Zunyi cohort of pregnant women from Southwest China. The study was conducted between August 2020 and July 2021, and urine samples were collected from 1003 pregnant women during their third trimester of pregnancy. The concentrations of nine phthalate metabolites in urine samples were then determined. Data on socio-demographic profiles of the participants, lifestyle during pregnancy, parity, and sampling season were collected using questionnaires. The detectable rate of phthalate metabolites ranged from 76–100%. On average, mono-butyl phthalate exhibited the highest median concentration (84.24 µg/L), while mono-benzyl phthalate exhibited the lowest median concentration (0.08 µg/L). Urine concentrations of phthalate metabolites were significantly higher in older, multiparous, higher-body mass index, higher-income, and passive-smoking during pregnancy participants. The levels of low-molecular-weight phthalate metabolites were highest during the summer. In light of our findings, phthalate metabolites present a demographic and seasonal differential distribution among the study population.