Placental growth factor (PGF)-expression within human atherosclerotic lesions is associated with plaque inflammation and neovascular growth. Serum levels of PGF and sFlt-1 (soluble fms-like tyrosine kinase-1, also known as soluble VEGF receptor-1) are altered in women with preeclampsia. Studies show that in both early and late onset preeclampsia, maternal serum levels of sFlt-1 are higher and PGF lower in women presenting with preeclampsia. In addition, placental sFlt-1 levels were significantly increased and PGF decreased in women with preeclampsia as compared to those with uncomplicated pregnancies. This suggests that placental concentrations of sFlt-1 and PGF mirror the maternal serum changes. This is consistent with the view that the placenta is the main source of sFlt-1 and PGF during pregnancy.