Microplastics in the human placenta: mechanisms, risks, and futures: a systematic review

Background: Micro- and nanoplastics have been detected in the human placenta, raising concerns regarding fetal development, immune programming, and long-term health. This systematic review synthesized evidence on their presence in placental and perinatal compartments, mechanisms of translocation across the maternal–fetal interface, and potential biological and perinatal health effects.Methods: PubMed, Embase, Web of Science, Scopus, the Cochrane Library, trial registries, and relevant reference lists were searched from inception to September 2025 without language or publication-date restrictions. Eligible studies included human observational studies, ex vivo placental models, in vitro trophoblast or placental cell experiments, and animal models investigating micro- or nanoplastics in placental or perinatal compartments. Reviews were included for contextual synthesis. Two reviewers independently screened studies, extracted data, and appraised quality using AMSTAR-2, ROBIS, or the Newcastle–Ottawa Scale, as appropriate. Findings were synthesized narratively because of methodological heterogeneity. Results: Of 1,226 records identified, 25 studies were included: eight human detection studies, two ex vivo placental models, two in vitro studies, two animal models, and eleven systematic, scoping, or narrative reviews. Microplastics were detected in placental tissue, cord blood, and meconium across multiple regions using μ-FTIR, Raman, LD-IR, and Py-GC/MS. Mechanistic studies demonstrated placental and trophoblast uptake and reported endoplasmic reticulum stress, apoptosis, oxidative stress, inflammatory responses, vascular impairment, and endocrine disruption. Human studies were limited by small sample sizes, inconsistent contamination-control procedures, heterogeneous analytical methods, and lack of standardized dosimetry. Overall certainty of evidence was low to moderate. Conclusion: Current evidence indicates that micro- and nanoplastics can reach the maternal–fetal interface and may adversely affect placental function. However, their clinical significance and long-term consequences remain uncertain. Standardized detection protocols, environmentally relevant dose–response studies, and prospective longitudinal investigations are urgently needed.