Patients are randomized in pairs by birth weight to receive either a placebo in arm I or tauroursodeoxycholic acid (TUDCA) in arm II. TUDCA is administered by mouth, nasogastric tube, or gastrostomy tube twice daily. After 2 weeks of therapy, a bile sample is obtained via a duodenal tube. An ultrasound examination of the liver and biliary tract is performed after 2 weeks and every 3 weeks thereafter until discontinuation of therapy or until presence of biliary tract sludge is noted on 2 consecutive examinations.