Performance of the FMF First-Trimester Preeclampsia Screening Model and Aspirin Prophylaxis Outcomes in Vietnam: A Prospective Cohort Study

Background Early identification of women at high risk of preeclampsia allows timely preventive interventions, particularly aspirin prophylaxis. The first-trimester screening model developed by the Fetal Medicine Foundation (FMF) combines maternal characteristics with biophysical and biochemical markers to improve prediction accuracy. Objective To evaluate the performance of the FMF first-trimester screening model for preeclampsia and to assess pregnancy outcomes following aspirin prophylaxis in high-risk women. Methods This prospective cohort study included 1,187 singleton pregnancies at 11 weeks 3 days to 13 weeks 6 days of gestation who underwent first-trimester preeclampsia screening at Quang Ninh Obstetrics and Pediatrics Hospital, Vietnam, between November 2023 and November 2025. Screening was performed using the FMF algorithm incorporating maternal characteristics, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), and placental growth factor (PlGF). Women identified as high risk received aspirin prophylaxis. Pregnancy and neonatal outcomes were subsequently analyzed. Results Among 1,187 screened pregnancies, 84 women (7.1%) were classified as high risk for preeclampsia. Each 1-mmHg increase in MAP was associated with an approximately 12.5% increase in the risk of preeclampsia, while each 0.1-unit increase in UtA-PI increased the risk by approximately 27.8%. Conversely, each 1 pg/mL decrease in PlGF was associated with a 7.0% increase in risk. The overall incidence of preeclampsia was 0.8% (9/1,187), with 66.7% of cases occurring in the high-risk group. No cases of early-onset preeclampsia (< 34 weeks) were observed, and most cases occurred at ≥ 37 weeks and were non-severe. Women who developed preeclampsia had lower gestational age at delivery and lower neonatal birth weight. Intrauterine growth restriction and neonatal intensive care unit admission were more frequent among pregnancies complicated by preeclampsia and among those classified as high risk. Conclusion First-trimester screening using the FMF model combined with early aspirin prophylaxis in high-risk women was associated with favorable maternal and neonatal outcomes. This strategy appears feasible and may be suitable for broader implementation in routine obstetric care in Vietnam.