Associations of urinary and follicular fluid phthalate exposure with salpingitis in women seeking fertility treatment.

Endocrine-disrupting chemicals are recognized for their impact on fallopian tube function; however, epidemiological evidence linking phthalates to fallopian tube disorders is still limited. In this cross-sectional study within the Tongji Reproductive and Environmental (TREE) Cohort, we collected urine and follicular fluid (FF) samples from 291 infertile women aged 20 to 45 years with no history of sexually transmitted infections (STIs) or pelvic inflammatory disease (PID), and measured eight phthalate metabolites. Salpingitis cases (n = 62) were identified based on clinical diagnosis documented in medical records. Notably, residual confounding by STI/PID-related factors may still exist despite this exclusion. We evaluated associations with individual metabolites and mixtures using logistic regression, Bayesian kernel machine regression (BKMR), and weighted quantile sum (WQS) regression models. In both crude and adjusted models, higher tertiles of monobenzyl phthalate (MBzP) in FF were positively associated with salpingitis (P for trend = 0.04). Upon adjusting for covariates, a per logarithm (ln)-unit rise in mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) levels in FF was linked to a 1.63-fold elevation (95% CI: 1.01, 2.64) in salpingitis odds. Furthermore, concentrations of monoethyl phthalate (MEP) in urine samples were positively correlated with salpingitis [adjusted model: 1.38 (1.06, 1.80)]. Additionally, the mixtures of phthalate metabolites in both urine and FF generally did not show significant associations with salpingitis. Stratified analyses revealed an increased odds of salpingitis associated with urinary mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) in women under 30 years of age (P for interaction = 0.03), with urinary MBzP in women with body mass index (BMI) ≥ 24 kg/m2 and non-female factor infertility (P for interaction = 0.01), and with FF mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) in the female-factor infertility group (P for interaction = 0.02). These results indicate that certain phthalate metabolites in FF and urine show a positive correlation with salpingitis, underscoring the necessity for further research.