Data collection and outcome measures
Maternal characteristics including age, parity, height, weight, the estimated date of confinement (EDC), gestational age (GA) at the time of blood sampling and the diagnosis PE were collected from the medical record. Blood pressure was measured at each visit of routine antenatal care by the standard protocol. The diagnosis of hypertensive disorders was made after delivery and was classified into gestational hypertension (GH), PE, chronic hypertension (chrHBP) and chrHBP with PE according to the standard of the American College of Obstetrics and Gynecology[1]. PE was stratified into early- and late-onset according to the occurrence before or after 34+0 weeks of gestation, respectively. Patients with any forms of HELLP syndrome (hemolysis, elevated liver enzyme, low platelet) and eclampsia were reclassified as PE. All the patients were managed by the standard clinical practice in our center regardless of the results of sFlt/PlGF ratios.