Nanoplastics, as an emerging persistent pollutant of global concern in recent years, have posed a potential threat to human health. However, there is little known about the adverse effects of nanoplastics on the female reproductive system. Here, polystyrene nanoplastics (PS-NPs) with a diameter of 50 nm were selected as representative nanosized plastic particles to investigate the potential effects of subchronic exposure on placenta development in mice.