Exposure to Phthalates and Alterations in Reproductive Hormones in Pregnant Women

Phthalates are ubiquitous environmental contaminants known for their endocrine-disrupting properties. Pregnancy is a particularly vulnerable period during which exposure to these compounds may adversely affect maternal health and fetal development. This study aimed to evaluate the exposure of pregnant women to phthalates, specifically diethyl phthalate (DEP), di-(2-ethylhexyl) phthalate (DEHP), and di-n-butyl phthalate (DnBP), and to investigate potential associations between urinary concentrations of their metabolites (MEP (monoethyl phthalate), MEHP (mono-(2-ethylhexyl) phthalate), and MnBP (mono-n-butyl phthalate)) and circulating reproductive hormone levels. A cross-sectional study was conducted on 384 pregnant women. Reproductive hormones (LH, FSH, testosterone, progesterone, estradiol, and prolactin) were quantified by electrochemiluminescence. Urinary concentrations of phthalate metabolites were measured using LC-MS/MS and normalized to creatinine levels. Phthalate metabolites were detected in the majority of samples (MEP: 97.4%; MEHP: 95.6%; MnBP: 92.9%). Mean concentrations were 83.50 ± 89.13 µg/g creatinine for MEP, 37.92 ± 41.08 µg/g for MEHP, and 44.64 ± 48.17 µg/g for MnBP. Phthalate detection frequencies did not differ significantly across residential regions, except for urinary MEHP concentrations, which were higher among women residing in the Eastern region of Algiers (53.039 µg/g creatinine). No significant differences in detection frequencies between 2022, 2023, and 2024 were observed; however, the highest urinary MEHP concentrations were recorded in 2022 (47.922 µg/g creatinine). Significant inverse associations were observed between urinary MEP and MEHP concentrations and plasma progesterone and testosterone levels (β_{MEP-progesterone}: - 0.216; β_{MEHP-progesterone}: - 0.523; β_{MEP-testosterone}: - 0.001; β_{MEHP-testosterone}: - 0.001). Estradiol levels were also negatively associated with MEP (β = - 23.301) and MnBP (β = - 33.241). Maternal exposure to phthalates was associated with alterations in reproductive hormone levels during pregnancy. These findings underscore the need to further investigate the potential implications of such hormonal disruptions for both maternal and fetal health.