Urinary phthalate metabolites in relation to serum anti-Müllerian hormone and inhibin B levels among women from a fertility center: a retrospective analysis

Phthalates, a class of endocrine disruptors, have been demonstrated to accelerate loss of ovarian follicle pool via disrupting folliculogenesis, and lead to diminished ovarian reserve. However, human data are limited. Here, we aimed to examine whether urinary phthalate metabolites are correlated with markers of ovarian reserve among women attending a fertility clinic. We measured eight phthalate metabolites in urine samples collected from 415 women seeking infertility treatment at the Reproductive Medicine Center of Tongji Hospital, Wuhan, China. Data on measures of ovarian reserve, as indicated by serum anti-Müllerian hormone (AMH) and inhibin B (INHB) levels, were retrieved retrospectively through electronic medical charts. Multivariate linear models were performed to estimate the associations of urinary phthalate metabolites and serum AMH and INHB. We further explored the potential nonlinearity of the relationships with restricted cubic spline analysis. Overall, we found largely null associations between urinary phthalate metabolites and serum AMH. The multivariable adjusted differences in serum INHB levels comparing the highest quartile of urinary MEHP to the lowest were - 18.29% (95% CI: - 31.89%, - 1.98%; P-trend = 0.04). Women in the second to fourth quartiles of MEOHP had a significant decrease of - 23.74% (95% CI: -35.85%, - 9.24%), - 19.91% (95% CI: -33.30%, - 3.82%) and - 20.23% (95% CI: -34.43%, - 2.96%), respectively, in INHB levels compared to the first quartile. In the spline analysis, we identified a nonlinear relationship between MEOHP exposure and serum INHB. We provided evidence for a negative association between urinary concentrations of certain phthalate metabolites and serum INHB levels, suggesting an adverse effect of phthalates exposure on growing antral follicles. Whether phthalates exposure at environmentally level will pose a risk for ovarian reserve needs further investigation.