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BACKGROUND The Fetal Medicine Foundation (FMF) proposed a competing risks model for early identification of women at high risk of preterm preeclampsia, typically associated with deep placentation disorders. The Great Obstetrical Syndromes include a spectrum of pregnancy complications (preeclampsia, intrauterine growth restriction, preterm birth, late spontaneous abortion, and abruptio placentae) that are also associated with deep placentation disorders. OBJECTIVE To estimate the rate of placenta-mediated pregnancy complications in nulliparous women with a positive first-trimester FMF preterm preeclampsia screening test. STUDY DESIGN We conducted a prospective cohort study of nulliparous women recruited at 11-14 weeks of gestation. Maternal characteristics, mean arterial blood pressure, levels of maternal serum biomarkers [pregnancy-associated plasma protein-A (PAPP-A), placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1)] and mean uterine artery pulsatility index were obtained to calculate the risk of preterm preeclampsia according to the FMF algorithm. The predicted risks were dichotomised as a positive or negative test according to two risk cut-offs (1 in 70 and 1 in 100). The detection rate, false-positive rate, and positive and negative predictive values were calculated for placenta-mediated complications, including preeclampsia, small for gestational age (birthweight <10th centile), fetal death, preterm birth and a composite outcome including any of the foregoing. The same analyses were computed for a composite of severe outcomes including preterm preeclampsia, severe small for gestational age (<3rd centile), and fetal death. RESULTS We included 4,575 participants with complete observations, of which 494 (10.8%) had an estimated risk of preterm preeclampsia ≥1 in 70 and 728 (15.9%) had a risk ≥1 in 100. The test based on a risk cut-off of 1 in 70 could have correctly predicted up to 27% of preeclampsia, 55% of preterm preeclampsia, 18% of small for gestational age, 24% of severe small for gestational age, and 37% of fetal deaths at a 10% false-positive rate. The test based on a cut-off of 1 in 100 could have predicted correctly up to 35% of preeclampsia, 69% of preterm preeclampsia, 25% of small for gestational age, 30% of severe small for gestational age, and 53% of fetal deaths at a 15% false-positive rate. The positive predictive value of a screening test for preterm preeclampsia ≥1 in 70, was 3% for preterm preeclampsia, 32% for the composite outcome and 9% for the severe composite outcome. CONCLUSIONS Nulliparous women with a first-trimester positive preterm preeclampsia FMF screening tests are at higher risk of both preterm preeclampsia, and other severe placenta-mediated pregnancy complications. Approximately 1 women out of 10 identified as high-risk by the FMF algorithm developed at least one severe placenta-mediated pregnancy complication.