Increased nuchal translucency and pregnancy outcome: a retrospective study of 1063 consecutive singleton pregnancies in a single referral institution

Abstract

The goals of this study are to assess pregnancy outcome with increased nuchal translucency (NT) and to determine the risk of adverse pregnancy outcome in relation to the degree of increased NT. All singleton pregnancies with increased NT at the first screening ultrasound examination referred to the Department of Fetal Medicine at the Helsinki University Central Hospital during 2002 to 2007 were included. Pregnancy outcomes and short-term outcomes of the newborns were recorded and analyzed. Of the 1063 pregnancies, karyotype was normal in 834 (78%). The majority, 611 (73%), of euploid fetuses was in the lowest NT group (95th percentile--3.4 mm). Percentage of favorable outcome decreased from 92% in the lowest NT group (95th percentile--3.4 mm) to 18% in the highest NT group (≥6.5 mm). Structural defects or genetic disorders were observed in 74 (9%) of cases with normal karyotype, of which 43 (58%) resulted in live birth, 25 (34%) in termination of pregnancy, and 6 (8%) in miscarriage or perinatal death. Even minimal (95th percentile--3.4 mm) increase in NT thickness is associated with adverse pregnancy outcome also in euploid fetuses.