Degree of maternal sedation was evaluated after administration of study drug. Neonatal ultrasound exams were performed at 3-5 days, 10-14 days, and 38-42 wks postmenstrual age; neonatal medications were recorded during the first week of life; treatments, and outcomes were recorded through death, discharge, or 120 days, whichever occurred first. Neurodevelopmental outcome was evaluated at 18-22 months corrected age by certified examiners masked to treatment status.