High risk neonates born at the threshold of viability: Does resuscitation improve survival over time?

Context: Extreme prematurity is the primary contributor to neonatal mortality in Colorado (CO). Neonatal mortality has been stable in CO for several years despite advancements in resuscitation of extremely premature infants calling into question the success of resuscitation in this patient population.

Design and Setting: Retrospective cohort study of Colorado birth and death certificate data from 1991-2003

Subjects: 2038 infants born at 22 weeks to 25 weeks gestation

Outcome measure: Neonatal survival (survival for 28 days after birth)

Results: Resuscitation, defined as any assisted ventilation after birth, for infants born at 22-25 weeks gestation ranged from 22% (1993) to 46% (1998). Although neonatal survival for infants 22-25 weeks gestation stayed constant at 40% between 1991 and 2003, fetal deaths decreased from 49% (of total births plus fetal deaths) to 31% over the same time period. Resuscitation was independently associated with survival (OR 2.80, 95% CI 2.20-3.56). Birth year had a marginal independent association with survival, as more infants born in 1991-1995 survived as compared to 2001-2003 (OR=1.40, 95%CI 1.04-1.88).

Conclusion: Resuscitation is associated with survival for Colorado infants born at the threshold of viability. However, survival for these infants did not increase over time despite upward trends in resuscitation and advancements in care of extremely premature infants. This may be explained by infants in later years being classified as deceased live births instead of fetal deaths.