OP-007 First-trimester preeclampsia screening for the detection of fetal growth restriction

Placental dysfunction is at the root of maternal complications such as preeclampsia (PE) as well as most cases of poor fetal growth. Given the shared underlying etiology, we aim to evaluate the performance of the FMF combined first-trimester PE screening at different cut-offs to detect fetal growth restriction (FGR) at any point of pregnancy.

Retrospective cohort study performed at a tertiary-level teaching hospital including singleton pregnancies with first-trimester PE screening and complete pregnancy outcomes with delivery at the same hospital between January 2023 and September 2023. The study was approved by the local Institutional Review Board. Gestational age was calculated according to crown-rump length at the first-trimester ultrasound. Screening was performed at 12 (11-14) weeks with PlGF determination at 11 (9-13) weeks. We categorized the risk into four groups, a basal one G0 (>1:200), G1 between 1:200 and 1:101, G2 between 1:100 and 1:51, and G3 ≥1:50. PE was defined as the presence of hypertension (≥140 / 90 mmHg) and proteinuria (≥300 mg/24 hours or a urine protein-to-creatinine ratio of ≥ 0.3). FGR was considered as a newborn weight <3rd customized centile according to GROW software. The main maternal basal characteristics as well as perinatal outcomes were collected from the clinical electronic history.
Descriptive analysis was performed using mean (standard deviation-SD) and median (interquartile range) or n (%) where appropriate. The performance of the screening to detect FGR was tested using logistic regression analysis, sensitivity, specificity, positive and negative predictive value, and the area under the ROC curve. Statistical analysis was computed using STATA 14.2 and significance was considered with p values <0.05 in a two-tailed distribution.

A total of 1831 screenings were performed, of which 1330 had complete pregnancy outcomes and composed the final study population. The mean (SD) maternal age was 31.8 (6.1) years old of which 48% were nulliparous, 3.9% had at least one major risk factor of PE, 11.8% had a history of fetal smallness, and 5.0% of previous PE.
Classification of the risk of preterm PE showed that 1127/1330 (84.7%) were part of of G0, 77/1630 (5.8%) of G1; 70/1330 (5.3%) of G2, and 56/1330 (4.2%) of G3.
The mean (SD) gestational age at delivery was 39.5 (2.1) weeks, with a mean weight of 3194 (493) g. The overall PE incidence was 5.0% and 1.7% of preterm PE. There were 45/1330 (3.4%) of newborns born <3rd centile of which 8/45 (17.8%) had concomitant PE. When compared with the G0 group, the RR for FGR was 2.4 (95%CI 0.9 – 6.3) for G1; 1.6 (95% CI 0.5 – 5.2) for G2, and 4.7 (95% CI 2.1 – 10.7) for G3.
Considering those at highest risk (G3), the performance of the screening to detect FGR had a sensitivity of 25% (95% CI 15.3% - 37%), specificity of 95.8% (95% CI 94.6% - 96.8%), positive predictive value of 23.3% (95% CI 14.2% - 34.6%), negative predictive value of 96.2% (95% CI 95% - 97.1%), and AUC of 0.60 (95% CI 0.55 - 0.66).

A very high risk (>1:50) of preterm PE in the first-trimester screening is strongly associated with both PE and FGR but is a poor predictor of fetal growth. Strategies later on during pregnancy should be established to early identify FGR and follow up in this particular group of women.