Definition of preeclampsia and endpoints
Primary endpoint was occurrence of preeclampsia as defined by the International Society for the Study of Hypertension in Pregnancy in 20183. In brief, the diagnosis of preeclampsia was persistent de novo gestational hypertension that develops at or after 20 weeks’ gestation accompanied by one or more of the following new-onset conditions: 1) proteinuria (>30 mg/dL); 2) other maternal organ dysfunction, including: acute kidney injury, liver involvement, neurological complications, hematological complications; 3) uteroplacental dysfunction (such as fetal growth restriction, abnormal umbilical artery Doppler wave form analysis, or stillbirth). Eclampsia was defined by new-onset of tonic-clonic, focal or multifocal seizures in the absence of other causative conditions such as epilepsy, cerebral arterial ischemia and infarction, intracranial hemorrhage, or drug use. Secondary endpoint was time to preeclampsia free survival, which was defined by the number of months free of preeclampsia between the 20th and 37th week of amenorrhea. Patients were censored after the 37th week of amenorrhea.