Intrauterine growth restriction (IUGR) is an important reason for premature delivery and has been reported to be associated with increased mortality, but in some studies paradoxically, improved morbidities. Data on neonatal outcomes for infants with IUGR at each viable gestational age at birth from large numbers of deliveries are lacking. More particularly, data on perinatal outcome related to an antenatal diagnosis of IUGR compared with a neonatal diagnosis are particularly deficient. Therefore, by using a large contemporary database, we evaluated the outcomes of neonates with IUGR and the gestational age–specific associations between growth restriction, morbidity, and mortality.

With the use of a database formed from a computer-assisted tool that generates clinical progress notes and discharge summaries on neonatal intensive care unit (NICU) admissions, we reviewed data on neonates discharged from 124 NICUs between January 1, 1997, and December 31, 2001. We evaluated singleton, inborn neonates who delivered between 23 and 34 weeks, excluding major congenital anomalies. We compared 3 measures of IUGR: antenatally diagnosed IUGR; a birth weight below the 10th percentile (small for gestational age [SGA]), and newborn infants with either or both of these diagnoses against a control group of gestational age–matched infants meeting none of these criteria whose birth weights were no greater than the 90th percentile.

Our sample included 29,916 prematurely born neonates; 1,451 (4.8%) with IUGR, 2,936 (9.8%) who were SGA, and 3,708 (12.3%) had at least 1 of these 2 markers. There were 22,798 (76%) normally grown control neonates. Within each gestational age group from 25 to 32 weeks, each marker of IUGR was associated with increased mortality, necrotizing enterocolitis, need for respiratory support at 28 days of age, and retinopathy of the premature. When corrected for gestational age, exposure to antenatal steroids, gender, and mode of delivery, these associations remained significant.

IUGR remains a serious problem that is associated with increased morbidity and mortality among prematurely born neonates, regardless of the definition used or whether the diagnosis is made antenatally or after birth. These results are important for obstetric counseling and decision making and for the anticipation and treatment of premature newborn infants.