Nuchal translucency is the thickening of a babyÕs neck, specifically in the back. This is usually noted between the 11th and 14th week of pregnancy and is the result of water accumulation under the baby's skin. The degree of thickness, or water accumulation, correlates directly with the probability of Down syndrome in the neonate. Therefore, as the volume of water in the neck increases, so too does the probability that the baby has Down syndrome. When the babyÕs chromosomes are normal (test results indicate that baby does not have Down syndrome) and nuchal translucency is still present, the risk for fetal cardiac defects increases substantially.