Objective: The purpose of this study was to examine the relationship between gestational age and outcomes of outborn versus inborn preterm infants.
Study design: Multivariable logistic regression analysis was used to examine gestational age-specific, risk-adjusted outcomes of 2962 singleton infants who were born at <32 weeks of gestation who were admitted to 17 Canadian neonatal intensive care units from 1996 through 1997.
Results: The risk-adjusted incidence was significantly (P <.05) higher among outborn versus inborn infants for mortality rates (odds ratio, 2.2) and > or =grade 3 intraventricular hemorrhage (odds ratio, 2.1) at < or =26 weeks of gestation and for chronic lung disease (odds ratio, 1.7) at 27 to 29 weeks of gestation. Outcomes of outborn and inborn infants at 30 to 31 weeks of gestation were not significantly different.
Conclusion: The short-term benefit of preterm birth at tertiary centers is related inversely to gestational age and may not extend beyond 29 weeks of gestation.