Exploring the Potential Impact of Nanoparticles on Fetal Development: An Updated Review

Nanomaterials are increasingly used in manufacturing, medicine, consumer products, and environmental technologies due to their unique physicochemical properties. Although these materials offer substantial technological and societal benefits, their widespread use has raised concerns about potential health risks. Of particular importance is exposure during pregnancy, as certain nanoparticles can cross the placental barrier and reach the developing embryo. Fetal tissues are highly sensitive to environmental insults, so maternal exposure to nanoparticles may disrupt normal development and increase the risk of abnormal pregnancy outcomes. This review examines the current understanding of nanoparticle-induced developmental toxicity, with a focus on the vulnerability of the maternal–fetal unit. We discuss the structure and function of the placental barrier and the mechanisms that enable nanoparticle transfer from mother to fetus. Particular attention is given to how nanoparticle characteristics, including size, shape, composition, and surface chemistry, influence biodistribution, placental transport, tissue accumulation, and toxicity. We summarize the major molecular and cellular mechanisms implicated in fetotoxicity, highlighting oxidative stress, apoptosis, autophagy, and DNA damage as recurring pathways identified across experimental studies. These interconnected processes contribute to placental dysfunction, impaired fetal growth, developmental abnormalities, and adverse pregnancy outcomes. We also compare findings across different classes of nanoparticles, including metal, metal oxide, carbon-based, and polymeric nanomaterials, identifying both shared toxicological mechanisms and material-specific effects. Evidence from animal models demonstrates that susceptibility varies according to nanoparticle properties, exposure conditions, and species, underscoring the complexity of nanoparticle–biological interactions and the limitations of extrapolating experimental findings directly to humans. Overall, the available evidence indicates that nanoparticle exposure during pregnancy represents a potential risk to fetal health, although important knowledge gaps remain regarding human exposure and long-term developmental outcomes. A better understanding of the mechanisms underlying nanoparticle-induced fetotoxicity is essential for improving human health risk assessment, refining experimental models, informing regulatory policies, and supporting the safe-by-design development of nanomaterials. Such knowledge will help ensure the responsible application of nanotechnology while minimizing potential risks during pregnancy. Finally, this review is distinguished by its integrated analysis of how the chemical characteristics of nanoparticles govern placental transfer and the mechanistic pathways of fetotoxicity across multiple nanomaterial classes, providing a unified framework that connects material properties with their potential for abnormal fetal development and adverse pregnancy outcomes.