Increased Nuchal Translucency and Fetal Chromosomal Defects

Abstract

The article by Taipale et al. (Dec. 4 issue)¹ raises further questions regarding methodologic flaws common in the literature on nuchal-translucency screening for Down's syndrome during the first trimester. The principal role of such screening is to detect fetuses with Down's syndrome in the 60 to 70 percent of pregnant women with no other risk factors for aneuploidy — namely, maternal age of more than 35 years or a previous pregnancy with Down's syndrome. Measuring nuchal translucency in women who already have these risk factors constitutes screening of a high-risk group, the results of which may not be applicable to a low-risk population. Although Taipale et al. excluded women more than 40 years old, how many of the women had an increased risk of Down's syndrome based on their being more than 35 years old?