Historically, most extremely premature infants
died within a few days after birth.3-5 Among extremely-
low-birth-weight infants born at centers
in the National Institute of Child Health and Human
Development (NICHD) Neonatal Research
Network between 1993 and 1997, immaturity was
the leading cause of death within 12 hours after
birth, and pulmonary conditions predominated
as the cause of death for those surviving for
more than 12 hours.