Defects and syndromes in chromosomally normal fetuses with increased nuchal translucency thickness at 10-14 weeks of gestation.

Increased fetal nuchal translucency thickness at 10-14 weeks of gestation is a common phenotypic expression of fetal chromosomal defects, structural abnormalities and genetic syndromes. This study reports on the prevalence of structural abnormalities and genetic syndromes in 4116 chromosomally normal pregnancies with increased fetal nuchal translucency thickness and reviews the relevant literature. In fetuses with increased nuchal translucency thickness, the prevalence of major cardiac defects, diaphragmatic hernia, exomphalos, body stalk anomaly and fetal akinesia deformation sequence is substantially higher than expected in the general population. In addition, there may be an association between increased nuchal translucency thickness and a wide range of rare skeletal dysplasias and genetic syndromes that are usually found in less than one in 10,000 pregnancies; however, the number of affected cases, both in the present and in previous series of fetuses with increased nuchal translucency thickness, is too small for definite conclusions to be drawn. The rates of miscarriage and perinatal death increase, whereas the rate of survival and the prevalence of live births with no obvious abnormalities decrease with increasing nuchal translucency thickness.