C3AR1 and preeclampsia: Recent research links reduced placental C3AR1 expression in preeclampsia to maternal blood pressure, implicating the janus kinase–signal transducer and activator of transcription (JAK-STAT), transforming growth factor-β (TGF-β), and hypoxia-inducible factor-1 (HIF-1) pathways, as well as NK cell/M1 macrophage activity (36).