Lead concentration in follicular fluid of infertile patients with and without endometriosis: a propensity score matching exploratory study.

OBJECTIVE

This preliminary study sought to provide initial insights into lead concentrations within the follicular fluid of infertile patients with and without endometriosis, tentatively observing any potential links between lead presence and the condition. Furthermore, we attempted to discern whether these levels might show a possible correlation with In Vitro Fertilization (IVF) outcomes.

METHODS

We conducted an exploratory retrospective observational case-control study at the Fertility Unit of the University of Campania Luigi Vanvitelli, utilizing propensity score matching to compare follicular fluid samples from infertile patients with and without endometriosis undergoing IVF from January 2022 to July 2024. The study's initial aim was to tentatively assess variations in lead concentration in the follicular fluid of women undergoing IVF with or without endometriosis. Additionally, a small-scale sub-analysis was performed to begin investigating how these follicular lead levels might relate to serum Beta-Human Chorionic Gonadotropin (hCG) positivity after embryo transfer in the endometriosis group.

RESULTS

In this preliminary evaluation, follicular fluid samples from 46 patients were analyzed, comprising 13 with endometriosis and 33 matched controls without. The median follicular lead concentration was notably higher in patients with endometriosis (2.07 µg/dL) compared to controls (0.63 µg/dL; p<0.001). Logistic regression analysis suggested a possible association between elevated lead levels and increased odds of endometriosis (OR: 14.6, 95% CI: 2.50-142.59, p = 0.007). In our further exploratory sub-analysis of endometriosis patients, 30.8% had positive serum Beta-hCG after embryo transfer but the variation in follicular lead concentration between positive serum Beta-hCG (1.00 µg/dL) and negative (2.54 µg/dL) was not statistically significant (p=0.12).

CONCLUSIONS

While our exploratory observations within this limited cohort suggest higher lead levels in the follicular fluid of patients with endometriosis compared to those without, these initial findings should be considered hypothesis-generating. Given the modest sample size, independent validation through larger, robustly designed prospective studies is essential.