This study of temporal trends in mortality among extremely premature infants receiving care in U.S. centers showed declines in overall mortality and in deaths from pulmonary causes, immaturity, infection, and CNS injury. Deaths from necrotizing enterocolitis increased. Although survival among premature infants has improved, prematurity is a leading contributor to neonatal mortality in the United States. 1 Approximately one in four extremely premature infants born at 22 to 28 weeks of gestation does not survive the birth hospitalization; mortality rates decrease with each additional week of completed gestation. 2 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 . . .