Pregnancy outcome of euploid fetuses with increased nuchal translucency: How bad is the news?

Aims: The number of fetuses with an abnormal increased first trimester nuchal translucency (NT), but confirmed normal karyotype and anatomy is relatively small and therefore a challenge for prenatal counseling. Universal guidelines are still needed for a systematic work-up, how to decide on the rewarding cut-off for this policy as well as how to counsel patients with an increased NT but with euploid fetuses. The current review aims to address some of these issues. Results: Eleven studies reporting on the pregnancy outcome of 2,128 euploid fetuses with increased NT (≥3 mm or ≥95 centile) were retrieved by our previously reported literature search. 2.2-10.6% of the fetuses has miscarried and 0.5-15.8% ended in perinatal death. There was an overall rate of 0.5-13% neurodevelopmental problems, and 2-8% of the malformations were undiagnosed before birth, the most common being cardiac anomalies. Nevertheless, 70-90% fetuses had normal outcomes. Conclusion: For those euploid fetuses with increased NT >2 MoM or ≥1.5 mm delta NT we recommend a detailed two-step anomaly scan including midgestation fetal echocardiography. Maternal age as well as data on relevant family history and persistence of nuchal edema provides additional relevant information for counseling and planning pregnancy management.