Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Research Network, January 1993 through December 1994

OBJECTIVES: Our purpose was to determine the mortality and morbidity rates for infants weighing 501 to 1500 g according to gestational age, birth weig ht, and gender. STUDY DESIGN: Perinatal data were collected prospectively on an inborn coho rt from January 1993 through December 1994 by 12 participating centers of t he National Institute of Child Health and Human Development Neonatal Resear ch Network and were compared with the corresponding data from previous repo rts. Sociodemographic factors, perinatal events, and the neonatal course to 120 days of life, discharge, or death were evaluated. RESULTS: Eighty-three percent of infants survived until discharge to home o r to a long-term care facility (compared with 74% in 1988). Survival to dis charge was 49% for infants weighing 501 to 750 g at birth, 85% for those 75 1 to 1000 g, 93% for those 1001 to 1250 g, and 96% for those 1251 to 1500 g . The majority of deaths occurred within the first 3 days of life. Mortalit y rates were greater for male than far female infants. Respiratory distress syndrome was the most frequent pulmonary disease (52%). Chronic lung disea se (defined as an oxygen requirement at 36 weeks after conception) develope d in 19%. Thirty-two percent of infants had evidence of intracranial hemorr hage. Periventricular leukomalacia was noted in 6% of infants who had ultra sonography after 2 weeks. The average duration of hospitalization for survi vors was 68 days (122 days for surviving infants weighing 501 to 750 g, com pared with an average of 43 days for surviving infants 1251 to 1500 g). Amo ng infants who died, the average length of stay was 19 days. CONCLUSIONS: The mortality rate for infants weighing between 501 and 1500 g at birth continues to decline. This increase in survival is not accompanie d by an increase in medical morbidity. There are interactions between birth weight, gestational age, sex, and survival rates.