L26/P-456 Association of microplastic exposure on fertility and pregnancy outcomes: An updated systematic narrative review

Abstract Study question Are microplastics present in human reproductive tissues, and are they associated with adverse pregnancy and fertility outcomes in humans? Summary answer Microplastics are found in human reproductive tissues and are associated with reduced sperm motility, lower fertilisation rates, and adverse pregnancy outcomes, though causality remains unproven. What is known already Microplastics (MPs) are ubiquitous environmental pollutants, and experimental studies suggest potential reproductive toxicity. Until recently, evidence of microplastics in humans has been limited. Improved analytical techniques now enable measurement of MPs in reproductive biological samples, but effects on fertility and pregnancy outcomes remain uncertain. Study design, size, duration A systematic narrative review of human studies published between database inception and 2025. Participants/materials, setting, methods An initial search was performed in MEDLINE, Embase, Emcare, CINAHL, ClinicalTrials.gov and ICTRP from inception to 03/02/2023. An updated search of MEDLINE was conducted from 2023 to 2025. Data were extracted on study characteristics, type of reproductive sample analysed, microplastic detection and associations with fertility and pregnancy outcomes. A narrative synthesis was performed. An initial systematic review identified 7 studies with a further 21 studies identified in a subsequent search, comprising of 2,109 participants. Main results and the role of chance Microplastics (MPs) have been detected in human reproductive tissues, including semen, follicular fluid, placenta, amniotic fluid, chorionic villi, umbilical cord tissue and blood, maternal blood and neonatal meconium. Across the 28 included studies, a total of 21 polymer types were identified, with the number of main polymers reported per study ranging from 2 to 9. Male fertility outcomes demonstrated the most consistent associations. Across three independent studies, higher MP burden in semen or seminal plasma was associated with reduced sperm motility. Two studies reported that higher MP levels in follicular fluid were associated with lower fertilisation rates in assisted reproduction settings, while no consistent associations were observed with implantation or clinical pregnancy. Placental MP presence was confirmed in 17 studies, six of which examined neonatal outcomes. Associations with adverse pregnancy outcomes, including miscarriage and pregnancy-induced hypertension, were reported in two studies. Nine studies incorporated lifestyle exposure data, most commonly assessing bottled water consumption and dietary habits, with several reporting associations between these factors and MP burden in reproductive tissues. Given the predominance of cross-sectional studies, small sample sizes in most studies, multiple comparisons and significant heterogeneity in detection methods and exposure metrics, the role of chance cannot be excluded. Limitations, reasons for caution The significant heterogeneity in detection methods and exposure metrics poses difficulties in direct quantitative comparisons. Potential contamination during sample handling and laboratory analysis remains another important limitation, as background microplastics may contribute to overestimation of exposure despite reported quality control and contamination prevention measures in most studies. Wider implications of the findings The presence of microplastics in human reproductive tissues is now well documented. Emerging evidence suggests potential negative effects on fertility and pregnancy outcomes. High-quality observational studies are required to support these findings. Trial registration number No