A prospective study was carried on in Cha hospital. Serum samples for Down syndrome screening were assayed to estimate pregnancy-associated plasma protein-A (PAPP-A), alpha-fetoprotein , unconjugated estriol, human chorionic gonadotrophin , and inhibin-A. Women screened for Down syndrome were offered UtA Doppler at 20-24 weeks of gestation and then collected serial serum samples for sFlt-1/PlGF ratio at two time points (24-27 and 34-37 weeks' gestation).
