Study population and blood collection
Two independent cohorts of pregnant women were assembled for this study. The testing cohort included sera from women between 25 and 31 wks’ of gestation with or without PE collected by ProMedDX Inc. (Norton, MA). Each woman had one sample collected. All PE samples were collected at the time of confirmative diagnosis. The validation cohort included sera from women who participated in a longitudinal study sponsored by the March of Dimes Prematurity Center at Stanford University between November 2012 and May 2016. Each woman had multiple sera collected from 5 to 29 wks’ of gestation prior to PE diagnosis. Study was approved by ethics committees at Stanford University with an IRB#21956 starting from Sep. 30th, 2011. Written informed consent was obtained from all participants.
The diagnosis of PE was made according to the American College of Obstetricians and Gynecologists criteria as follows: a persistent systolic blood pressure ≥140 mmHg, or a diastolic blood pressure ≥ 90 mmHg after 20 wks’ of gestation in a woman having a previous normal blood pressure in conjunction with one or more of the following: new-onset proteinuria, new-onset thrombocytopenia, impaired liver function, renal insufficiency, pulmonary edema, or visual or cerebral disturbances in the absence of proteinuria. Early-onset PE was defined as PE that develops before 34 wks’ of gestation, whereas the late-onset PE develops at or after 34 wks’ of gestation.