Considering that there are few studies on PIWI/piRNA in the pathogenesis of preeclampsia, we want to understand the role of the PIWI/piRNA pathway in the pathogenesis of preeclampsia, its impact on the proliferation and invasion of placental trophoblast, and which piRNAs may be involved in the occurrence of the disease. The gene discussed is PIWIL1; the disease is preeclampsia.