Objective: Previous studies that compared outcomes of infants born outside tertiary care centers (outborn) with those born in tertiary care centers (inborn) did not account for admission illness severity and perinatal risks. The objective of this study was to examine whether outborn status is associated with higher mortality and morbidity, after adjustment for perinatal risks and admission illness severity (using the Score for Neonatal Acute Physiology, Version II [SNAP-II]) among preterm infants who were admitted to Neonatal Intensive Care Units (NICUs).
Methods: Logistic regression analysis was used to compare the risk-adjusted outcomes of 3769 singleton infants born at or before 32 weeks' gestation, who were admitted to 17 Canadian NICUs during 1996-1997.
Results: Outborn and inborn infants had significantly different gestational ages, perinatal risk factors (maternal hypertension, prenatal care, antenatal corticosteroid therapy, 5-minute Apgar score, delivery type, small for gestational age) and admission SNAP-II. Outborn infants were at higher risk of death (adjusted odds ratio [OR] 1.7, 95% confidence interval [CI] 1.2, 2.5), grade III or IV intraventricular hemorrhage (adjusted OR 2.2, 95% CI 1.5, 3.2), patent ductus arteriosus (adjusted OR 1.6, 95% CI 1.2, 2.1), respiratory distress syndrome (adjusted OR 4.8, 95% CI 3.6, 6.3), and nosocomial infection (adjusted OR 2.5, 95% CI 1.9, 3.3), even after adjusting for perinatal risks and admission illness severity.
Conclusions: Outborn infants were less mature and more ill than inborn infants at NICU admission. However, even after adjustment for perinatal risks and admission illness severity, inborn infants had better outcomes than outborn infants. Our results support in-utero transfer of high-risk pregnancies to a tertiary level facility.