The impact of microplastics on the human reproductive system: a narrative review.

Microplastics (MPs), plastic particles smaller than 5 mm, are ubiquitous environmental contaminants and have been reported in human blood, placenta, semen, testis, ovarian follicular fluid, and penile tissue. This narrative review examines evidence relevant to reproductive and sexual health, with emphasis on endocrine signaling, oxidative stress, inflammation, and possible multigenerational effects. Human studies currently demonstrate tissue detection and, in cross-sectional semen studies, associations with selected semen parameters; they do not establish causation. In rodents, fish, invertebrates, and in vitro systems, MP exposure has been associated with impaired spermatogenesis and steroidogenesis, ovarian granulosa-cell injury, altered oocyte maturation, placental dysfunction, and reduced erectile function. Evidence concerning pregnancy outcomes and assisted reproductive technology (ART) remains predominantly experimental or hypothetical. The available literature therefore supports biological plausibility and the need for standardized exposure assessment and longitudinal human studies, but not firm clinical risk estimates or causal conclusions.