Cohort of increased nuchal translucency in the first trimester without pathogenic variant on chromosomal microarray...

Increased nuchal translucency (NT) in the first trimester is often linked to chromosomal anomalies and fetal malformations.

To assess fetal, neonatal, and two-year developmental outcomes in fetuses with NT ≥ 3.5 mm and normal chromosomal microarray analysis (CMA).

This single-centre retrospective study included all singleton pregnancies between 2015 and 2021 with NT ≥ 3.5 mm at first-trimester ultrasound and no pathogenic CMA variant. Data on psychomotor development at 2 years were collected.

Among 131 pregnancies, there were 41 perinatal deaths (31%): 9 fetal deaths, 27 medically indicated terminations of pregnancies, and 5 neonatal deaths. Of the 90 children surviving beyond 28 weeks, 77 (85.6%) had no malformation, while 13 (14.4%) presented one or more anomalies. Perinatal death was significantly associated with NT > 6 mm (P < 0.001), malformation detected on first- or second-trimester ultrasound (P < 0.01), and persistent NT at 22 weeks (P < 0.001). At 2 years, 5 of the 90 children (5.5%) showed neurodevelopmental delay.

In the absence of a pathogenic CMA variant, an isolated, moderately increased NT that regresses in the second trimester is generally associated with favorable outcomes, offering reassuring information for prenatal counseling.