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Comment on “Relationship of first‐trimester uterine artery Doppler to late stillbirth”

I read with great interest the article by Iacovella et al. The authors reported that high first-trimester uterine artery Doppler (UAD) resistance index was associated with late stillbirth after 34weeks’ gestation. They rightly explained this association by the link between high first-trimester UAD resistance index and poor placental development leading to fetal growth restriction even though the birth weight can be ‘almost’ normal. However, more than the sole first trimester UAD, the sequence of changes in uterine flow between the first and second trimesters is associated with the complications related to impaired placentation. Using the persistence of an abnormal mean pulsatility index in a sequential two-step screening at 11 to 14 then 19 to 22weeks, Gomez et al. identified among 870 unselected singleton pregnancies the group with persistent abnormal mean pulsatility index from the first to the second trimester as the group with the greatest risk for adverse perinatal outcome defined as hypertension or fetal growth restriction (odds ratio, 10.7; 95% confidence interval, 3.7–30.9). Still more precisely Plasencia et al. showed that the decrease in impedance between 11 and 14weeks and 21 to 25weeks was steeper in pregnancies with a normal outcome than in those with subsequent pre-eclampsia. The persistence of abnormal UAD waveforms (with persistent notch) at 12 to 14 then 22 to 24weeks of gestation may indicate impaired placentation. In this group we previously showed that the highest rate of complications related to placental insufficiency (pre-eclampsia, fetal growth restriction, fetal death, abruptio placentae), and we and others found that the lowest mean birth weight was observed. In contrast, rates of complications decreased and higher birth weights were observed with early disappearance of notching at 12 to 14weeks. The observations that the women with ‘late and/or partial normalization’ at 21 to 25weeks of UAD impedance had intermediate birth weight newborn may support the authors’ hypothesis that mild fetal growth restriction is underlied by mild placental insufficiency (which could also explain the link of abnormal first-trimester UAD to late stillbirth). These observations are in line with the authors’ observation that birth weight centile is significantly lower in the ‘Late stillbirths’ group but results in ‘almost normal weight fetuses’, only smaller than they should be. This could also argue in favor of the clinical utility of first trimester UAD, and closer follow-up care starting from 34weeks even in the case of an apparent ‘normalization’ of UAD at 21–25weeks.