Microplastics in the Perinatal Period: Emerging Evidence on Maternal Exposure, Placental Transfer, and Fetal Health Outcomes

Abstract Microplastic pollution has emerged as a pervasive environmental and biomedical concern, with particles < 5 mm identified in drinking water, air, food, and human tissues. Recent studies have detected microplastics in maternal blood, placental tissue, amniotic fluid, cord blood, and breast milk, raising profound concerns about in utero exposure and its implications for fetal development. The maternal-fetal interface is uniquely vulnerable, yet the health impacts of microplastic translocation across gestational barriers remain poorly understood. This narrative review synthesizes the current scientific literature on microplastic exposure during the perinatal period. We analyze peer-reviewed studies from human cohorts, in vivo animal models, and in vitro placental simulations to examine the extent of maternal exposure, routes of fetal transmission, and biological consequences. Evidence is organized according to toxicological mechanisms, including oxidative stress, inflammation, endocrine disruption, immune modulation, and potential epigenetic effects. Placental permeability, dose thresholds, and particle size-dependent dynamics are explored in depth. The emerging evidence suggests that microplastics may impair placental integrity, modulate immune responses, alter fetal growth trajectories, and potentially affect neurodevelopment. However, findings remain heterogeneous due to methodological variation in particle characterization, exposure measurement, and outcome reporting. Several studies indicate consistent signs of proinflammatory and oxidative stress responses within placental tissues. This review highlights critical research gaps – including standardized exposure metrics, longitudinal cohort data, and human-relevant toxicity thresholds – and proposes a translational framework to guide future studies. Understanding microplastic impacts on early human development is essential for shaping global health policies and maternal-fetal environmental protections.