Growth patterns of extremely low-birth-weight hospitalized preterm infants

Objective: To characterize the growth of extremely low-birth-weight (ELBW) infants during hospitalization in terms of weight gain, growth velocity and relative change in weight. Design: Retrospective, descriptive design. Setting: Two neonatal intensive-care units located in the midwestern United States. Patients: Thirty-five ELBW infants with a birth weight less than 1,000 g and appropriate for gestational age. Main Outcome Measures: Clinical data related to the infant's growth and nutrition were obtained from a chart review. Birth weight and discharge weight were compared following conversion of the weights to z scores. The discharge weight was compared to the median weight of a fetus of comparable gestational age based on an intrauterine growth reference. Growth velocity was determined (grams/day). Results: Weight-for-age z scores decreased significantly between birth and discharge. By discharge, 89% of the infants had discharge weights less than the 10th percentile. The mean discharge weight was significantly less than the median weight of a fetus of comparable gestational age. Days to regain birth weight significantly affected growth outcomes. Conclusion: ELBW infants develop a growth deficit during the first few weeks of life that not only persists but also worsens during hospitalization. Potential causes of this growth deficit include the medical and nutritional management that are part of the usual care of ELBW infants. Because these infants are discharged with this growth deficit, catch-up growth will have to occur at home.