NICHD Neonatal Research Network (NRN): Extremely Preterm Birth Outcome Data

How were the data collected, and what factors were used to determine the outcomes?

Between 1998 and 2003, researchers at NRN sites gathered information on 4,446 preterm infants born at the hospitals within the NRN.

Typically, health care providers consider the estimated gestational age of a preterm infant to help determine his or her possible outcomes. Researchers in the NRN have discovered that the inclusion of additional factors provides a more accurate way to estimate infant outcomes than using gestational age alone.

These outcome data are based on five factors, including:

  • Gestational age—This factor refers to the best obstetric estimate of completed weeks of gestation.  These outcome estimates are based on the 4,446 infants whose best obstetric estimate of gestational age in completed weeks was 22 weeks to 25 weeks at birth.
  • Birth weight (in grams)—This factor ranges from 401 grams to 1,000 grams, the average weight range of the infants included in this sample.
  • Sex
  • Singleton birth—Infants included in this sample were from single and multiple pregnancies. Infants in multiple pregnancies (e.g., twins or triplets) had outcomes that differed from those of infants from single pregnancies.
  • Antenatal corticosteroids—This factor refers to whether or not the mother received any corticosteroids before birth to help the infant’s lungs mature.

PLEASE NOTE: The information on this website is intended to better inform health care providers and families about possible infant outcomes based on standardized assessments.  It is not intended to be the only information that care decisions are based on, nor is it intended to be a definitive means of predicting infant outcomes.  Users should keep in mind that every infant is an individual, and that factors beyond those used to formulate these standardized assessments may influence an infant’s outcomes. 

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