Abstract
INTRODUCTION: Our objective was to compare the predictive performance of the Fetal Medicine Foundation (FMF) competing-risk model for preterm preeclampsia (PE) screening using placental growth factor (PlGF) measurements obtained at 11-13(+6) weeks versus before 11 weeks of gestation. MATERIAL AND METHODS: This multicenter prospective cohort study included women with singleton pregnancies attending their routine first-trimester assessment (11(+0) to 13(+6) weeks) in four hospitals across Spain from 2021 to 2023. Maternal characteristics, biophysical parameters (mean arterial pressure and uterine artery pulsatility index), and biochemical markers (PlGF measured twice in each woman, before 11 weeks and between 11 and 13(+6) weeks) were assessed. Risk assessment for preterm PE was estimated by the FMF algorithm. Predictive performance was evaluated by comparing detection rates (DR) at different fixed screen-positive rates (SPR), area under the receiver-operating characteristic curve (AUROC), and calibration plots. Statistical adjustments were made to account for prophylactic aspirin use. RESULTS: The study population comprised 3448 women, including 19 (0.55%) who developed preterm preeclampsia and 47 (1.36%) who developed term preeclampsia. At 10% SPR, the detection rates (adjusted for aspirin use) were highest for the model incorporating PlGF between 11 and 13(+6) weeks (72.9%; 95% CI, 42.2%-90.9%), compared to models with PlGF before 11 weeks (66.4%; 95% CI, 39.9%-85.4%) and without PlGF (66.0%; 95% CI, 39.3%-85.3%). Similar trends were observed at higher SPR thresholds. The best discrimination (AUROC: 0.863; 95% CI, 0.754-0.971) and calibration were also achieved by the model using PlGF between 11 and 13(+6) weeks. CONCLUSIONS: PlGF measured before 11 weeks did not improve preterm PE screening performance. Due to the small number of cases, further validation is needed. Maternal and biophysical markers remain a viable alternative when PlGF is unavailable.