Assessing microplastics as a novel threat to maternal-fetal health: Placental barrier penetration and fetal developmental consequences

Microplastics (MPs) are now ubiquitous environmental contaminants that pose major risks to the environment and ecosystem, and in the last decade, concern about their potential threats to the reproductive system has gained widespread recognition. MPs can readily pass through biological barriers such as the placental and blood-brain barriers due to their small size. The ability of MPs to cross the placental barrier causes utmost concern as they could pass to the next generation and affect the health of the offspring. This review addresses the placental biology and its barrier function, as well as the ability of the MPs to translocate across the placenta. It also draws emphasis to responses of the placenta to the exposure of MPs at the cellular level, in vivo animal models, and human studies. To give a thorough grasp of the impacts of MPs at the maternal-fetal interface, investigations on the effects of MPs on fetal growth and development are also extensively reviewed.