Placental growth factor (PIGF), a member of the vascular endothelial growth factor (VEGF) subfamily, is a key molecule in angiogenesis, especially in embryonic development. During pregnancy, the placental trophoblast is the main source of PIGF. Many other tissues, including villous trophoblast cells, also express PIGF. PIGF expression in human atherosclerotic injury is associated with plaque inflammation and neovascularization. In early-onset and late-onset preeclampsia, maternal serum sFlt-1 levels are higher and PIGF levels are lower.