Risk factors for neonatal mortality among extremely-low-birth-weight infants

Am J Obstet Gynecol. 2005 Mar;192(3):862-7. doi: 10.1016/j.ajog.2004.07.029.


Objective: The purpose of this study was to examine characteristics associated with neonatal mortality among extremely low-birth-weight infants (< or = 1000 g).

Study design: A population-based, case-control study using linked Missouri birth and death certificates from 1989 to 1997 was conducted. Cases (n = 835) were defined as extremely low-birth-weight infants that died within 28 days of birth. Controls (n = 907) were randomly selected from extremely low-birth-weight infants that were alive at 1 year and were frequency matched to subjects by birth year and birth weight.

Results: Infants born with severe congenital anomalies and at the youngest gestational ages were at greatest risk for neonatal mortality. Other significant risk factors included maternal age (< 18 and > 34 years), vaginal delivery, nontertiary hospital care, malpresentation, male gender, and small for gestational age. Black race and preeclampsia were protective against early death.

Conclusions: The risk of neonatal mortality among extremely low-birth-weight infants was associated with several maternal, infant, and obstetric factors, some of which may be preventable.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Case-Control Studies
  • Congenital Abnormalities / mortality
  • Continental Population Groups
  • Female
  • Gestational Age
  • Humans
  • Infant Mortality*
  • Infant, Newborn
  • Infant, Very Low Birth Weight*
  • Labor Presentation
  • Male
  • Maternal Age
  • Pre-Eclampsia
  • Pregnancy
  • Risk Factors
  • Sex Factors