Associations between concentrations of microplastics in follicular fluid and the risk of diminished ovarian reserve

Microplastics (MPs) have been detected in various human tissues, but their association with ovarian health remains unclear. This exploratory study aimed to identify and quantify MPs in the follicular fluid of individuals with diminished ovarian reserve (DOR) and explore potential associations. We conducted a case-control study of 25 patients with DOR and 20 control patients with tubal factor infertility. Pyrolysis-gas chromatography-mass spectrometry, laser direct infrared spectroscopy, and scanning electron microscopy were used to analyze MPs properties, types, and abundance. MPs were present in the follicular fluid of both groups. Total MPs abundance was significantly higher in the DOR group (30.63 μg/g vs. 18.48 μg/g in controls), with elevated levels of polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) (p < 0.05). After controlling for potential confounding factors, PE (adjusted OR = 2.529, 95 % CI: 1.007-6.354, p = 0.048), PVC (adjusted OR = 1.223, 95 % CI: 1.009-1.483, p = 0.040), and total MPs levels (adjusted OR = 1.174, 95 % CI: 1.011-1.363, p = 0.036) remained associated with DOR risk. Total MPs, PE, and PVC abundance showed negative correlations with anti-Müllerian hormone levels, and total MPs negatively correlated with antral follicle count (p < 0.05). Mouse exposure models showed that MPs exposure was associated with ovarian functional and morphological changes. This study provides the first evidence of MPs-DOR associations, offering new insights into environmental impacts on female reproductive health.