Survival of pre-viable preterm infants in the United States: a systematic review and meta-analysis

Semin Perinatol. 2013 Dec;37(6):389-400. doi: 10.1053/j.semperi.2013.06.021.


The objective of this paper is to review observational studies that addressed the survival of pre-viable gestations in the United States. We searched PubMed, Ovid, CINAHL, and Web of Knowledge for studies reporting survival of infants born at <24 gestational weeks and/or <500g in the United States and published between January 2003 and January 2013. The full texts of 70 articles were examined and a total of 15 studies qualified and were selected. We analyzed fixed-effect and random-effects models for eight studies on survival to discharge. Pooled survival to discharge in the random-effects model was 45.9% (95% CI: 41.1-51.7) and 39.7% in the fixed-effect model (95% CI: 38.8-40.7). Studies differed by pre-viable survival measures and epochs (1985-2009). Protective factors included antenatal corticosteroids, neonatal resuscitation, and intensive care. The current survival threshold for pre-viable infants warrants reconsideration of the limits of viability. Protective factors that enhance survival should be considered in the management of these infants.

Keywords: Extremely low birth weight; Extremely preterm birth; Periviable; Pre-viable; Pregnancy; Survival.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Female
  • Fetal Viability*
  • Humans
  • Infant Mortality
  • Infant, Extremely Low Birth Weight*
  • Infant, Extremely Premature*
  • Infant, Newborn
  • Infant, Premature*
  • Maternal-Child Health Centers / organization & administration*
  • Policy Making
  • Pregnancy
  • Survival Analysis
  • Survival Rate
  • United States / epidemiology