<qa>  What is the name of the study that is funded by the NHLBI?Baby TCD is an ancillary study to the initial phase of BABY HUG, a multicenter clinical trial funded by the NHLBI. In BABY HUG, infants 12-17 months old with sickle cell disease SCD will be randomized to either hydroxyurea HU or placebo and followed for 24 months. There is broad interest in the effect of hydroxyurea on the central nervous system in the children being studied. Stroke occurs after age 1 year and there is evidence that the process of cerebrovascular disease starts very early in some patients. The Cooperative Study of Sickle Cell Disease documented a high risk of incident stroke in the 2-6 year age group. The study is in response to an initiative on Ancillary Studies in Heart, Lung, and Blood Disease Trials released in June, 2000. 