Pregnancy outcome for fetuses with increased nuchal translucency but normal karyotype.

Objective: To investigate pregnancy outcome for fetuses with nuchal translucency (NT) ≥3.5 mm but normal karyotype in the Stockholm (Sweden) area.
Methods: A retrospective population-based cohort study. From 2006 to 2012, fetal NT was measured in 55123 singleton pregnancies. There were 341 pregnancies with NT thickness ≥3.5 mm; 139 had a normal karyotype, 164 had an abnormal karyotype and 38 were removed from the study. Pregnancy outcome was defined as adverse (termination of pregnancy [TOP], miscarriage [MC], intrauterine fetal death [IUFD], or delivery of a child with structural defects or genetic disorders), or favourable (delivery of a child without any structural defects or genetic disorders diagnosed before discharge).
Results: Of the 139 high NT pregnancies with normal karyotype, 110 (79.2%) resulted in live births, one (0.7%) IUFD, 23 (16.5%) TOP and five (3.6%) MC. The risk of an adverse pregnancy outcome increased with increasing NT. Structural fetal defects were found in 28 (19.5%) of pregnancies undergoing second trimester ultrasound screening, of which seven resulted in live births and 21 were terminated. The most common structural defect was cardiac defects.
Conclusions: Adverse pregnancy outcome increased with increasing NT, even with normal karyotype, however, the prognosis is good if the second trimester ultrasound screening is normal.
(© The Author(s) 2015.)