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Updated: May 16, 2026
The 4-vessel Sampling Approach to Integrative Studies of Human Placental Physiology In Vivo
Published on: August 2, 2017
Improved risk stratification for placenta-mediated complications through the use of mid-gestational uterine artery
Christina Ammari1, Raffaele Napolitano1,2, Daniel Stott2
1Institute for Women's Health, University College London, London, UK.
Introduction:
Placenta-mediated complications such as pre-eclampsia (PE), fetal growth restriction (FGR), and preterm birth (PTB) remain leading causes of maternal and perinatal morbidity. First-trimester screening tools, including the Fetal Medicine Foundation (FMF) algorithm and National Institute for Health and Care Excellence (NICE) criteria, help identify women at risk, but their predictive accuracy remains limited. This study evaluated whether second-trimester uterine artery (UtA) Doppler measurements provided additional risk stratification within risk groups defined by either FMF or NICE-based first-trimester screening.
Material And Methods:
This was a retrospective cohort study which included 5518 singleton pregnancies managed at University College London Hospital between 2019 and 2022. Women were stratified into four risk groups based on first (1) and second (2) trimester assessments: L1L2 (low risk in both trimesters), L1H2 (low risk in first, high risk in second), H1L2 (high risk in first, low in second), and H1H2 (high risk in both trimesters). First-trimester risk was assessed using FMF or NICE models; second-trimester high risk was defined as a mean UtA pulsatility index (PI) ≥95th centile. Primary outcomes included the incidence of PE, small for gestational age (SGA; birthweight <10th centile), FGR (<3rd centile), PTB before 34 and 37 weeks, stillbirth, and a composite adverse outcome (PE, FGR, PTB, or stillbirth). Secondary outcomes were emergency cesarean section (EMCS), neonatal intensive care unit (NICU) admission, and NICU length of stay. This study was not designed to compare the intrinsic screening performance of NICE and FMF as first-trimester tools.
Results:
Women classified as low risk in the first trimester but high risk in the second trimester had higher rates of adverse outcomes compared to those who remained low risk in both trimesters in both FMF- and NICE-based stratification. Notably, women classified as high risk in both trimesters had the highest rates of placenta-mediated complications, including PE, FGR, PTB, and stillbirth. This pattern was consistent across both first-trimester risk frameworks.
Conclusions:
Mid-gestational UtA Doppler assessment improves prediction of placenta-mediated complications when included with FMF or NICE screening. This two-step approach enhances identification of high-risk pregnancies and supports more personalized antenatal care.
