- OBJECTIVE: The purpose of this study was to examine prospectively the association between increased nuchal translucency thickness and major cardiac defects in chromosomally normal fetuses. STUDY DESIGN: A prospective cohort study of 263 chromosomally normal fetuses with an increased nuchal translucency thickness at 11 to 14 weeks of gestation at a tertiary referral center was performed. The incidence of major cardiac defects was examined in relation to the fetal nuchal translucency thickness at the 11 to 14 week ultrasound examination. RESULTS: The nuchal translucency thickness measurements ranged from 2.2 to 8.0 mm (median, 3.1 mm). There were 13 cases of major cardiac defects in this cohort, which gave a prevalence of 49.4 of every 1000 fetuses. With the use of the 99th percentile of nuchal translucency thickness, the prevalence rose to 106.7 of every 1000 fetuses. CONCLUSION: In this population of chromosomally normal fetuses with an increased nuchal translucency thickness, the incidence of cardiac defects was high, which suggests that fetal echocardiography is indicated in this group.