Preeclampsia (PE) occurs in 2-5% of pregnant women and can increase maternal and fetal mortality in the perinatal period. Small doses of aspirin given to pregnant women at high risk of PE before 16 weeks can reduce the incidence of PE by more than 50%, so predicting the risk of PE early in pregnancy is critical. Maternal serum pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PLGF) and ultrasound measurement of uterine artery pulsatility index are good predictors of the risk of PE.