Micro and Nanoplastics and Obstetric Outcomes in Humans and Animals: A Systematic Review

Background: Micro- and nano-plastics (MNPs) are pervasive environmental contaminants that accumulate in various tissues, including the placenta. Experimental and clinical studies suggest potential cytotoxic, oxidative, and inflammatory effects that may lead to placental dysfunction and adverse obstetric outcomes. However, high-quality evidence on the clinical relevance of MNPs exposure during pregnancy remains scarce, underscoring the need for systematic evaluation of their impact on maternal and fetal health. Methods: The databases PubMed, ScienceDirect, CENTRAL, Embase, MDPI and Google Scholar were searched for studies published up to September 2025 investigating the relationship between MNPs and obstetric outcomes. Results: Twelve studies were included in this review, with half employing an observational design in human subjects and the other half using experimental studies in murine models. Although the available evidence is limited, there are studies reporting the association between MNPs exposure and premature birth, low birth weight, intrauterine growth restriction, and miscarriage. The most prevalent polymer detected was polyethylene, and the most commonly used MNPs detection techniques were Raman microspectroscopy, digital microscopy, Fourier Transform Infrared, and Pyrolysis gas chromatography-mass spectrometry. Conclusions: This systematic review summarizes current limited insights on the potential effects of MNPs on obstetric outcomes, highlighting possible associations with low gestational age, low birth weight, intrauterine growth restriction, and miscarriage. Findings do not allow causal inference due to heterogeneity in study design, exposure assessment, contamination control, and analytical methodologies.