The study was renewed in 2002 to continue research in the evolving risk factors and outcomes of bronchopulmonary dysplasia (BPD) and other neonatal conditions of very low birth weight (VLBW, < 1500g) infants and children. The renewal will comprehensively document the neonatal and early childhood course and outcomes of all VLBW births in Wisconsin occurring during the calendar years 2003 and 2004 (800-850 per year), using established methodology with added risk factor information to examine currently proposed inflammatory hypotheses of BPD etiology. The study will also implement and validate new diagnostic criteria for the severity of BPD developed by a recent NIH workshop.