Pregnancy outcomes with increased nuchal translucency after routine Down syndrome screening

The purpose of this study was to evaluate the outcomes of pregnancies with nuchal translucency greater or equal to 3 mm for routine first trimester screening in unselected populations.

A total of 2980 pregnant women for first trimester ultrasonography were routinely offered crown-rump length (CRL) and nuchal translucency (NT) for screening for Down syndrome between 11 and 14 weeks' gestation. A complete follow-up was obtained in all cases by a review of medical records.

Using a cut-off value of 3 mm, the prevalence of increased fetal NT was 0.7% (n=22). Among the 22 cases, there were five (22.7%) chromosomal abnormalities. Of the 17 chromosomally normal pregnancies, four resulted in fetal demise (spontaneous abortion, intrauterine death or termination of pregnancy due to fetal abnormalities). The remaining 13 pregnancies resulted in live births, including one gestational hypertension and one preterm delivery, respectively. The total incidence of an adverse outcome in the group of increased fetal NT was 45.5%.

In a routine population with first-trimester ultrasonography, fetal NT measuring greater than or equal to 3 mm was associated with a poor pregnancy outcome with not only chromosomal abnormalities and congenital cardiac diseases, but also poor maternal and fetal health or adverse pregnancy outcomes. In addition, this study also demonstrated the necessity for fetal assessment and follow-up in cases where the fetal NT is increased in the first trimester.