Weight Growth Velocity and Postnatal Growth Failure in Infants 501 to 1500 Grams: 2000-2013

Abstract

Background: Very low birth weight infants often gain weight poorly and demonstrate growth failure during the initial hospitalization. Although many of the major morbidities experienced by these infants during their initial NICU stays have decreased in recent years, it is unclear whether growth has improved.

Methods: We studied 362 833 infants weighing 501 to 1500 g without major birth defects born from 2000 to 2013 and who were hospitalized for 15 to 175 days at 736 North American hospitals in the Vermont Oxford Network. Average growth velocity (GV; g/kg per day) was computed by using a 2-point exponential model on the basis of birth weight and discharge weight. Postnatal growth failure and severe postnatal growth failure were defined as a discharge weight less than the 10th and third percentiles for postmenstrual age, respectively.

Results: From 2000 to 2013, average GV increased from 11.8 to 12.9 g/kg per day. Postnatal growth failure decreased from 64.5% to 50.3% and severe postnatal growth failure from 39.8% to 27.5%. The interquartile ranges for the hospitals participating in 2013 were as follows: GV, 12.3 to 13.4 g/kg per day; postnatal growth failure, 41.1% to 61.7%; and severe postnatal growth failure, 19.4% to 36.0%. Adjusted and unadjusted estimates were nearly identical.

Conclusions: For infants weighing 501 to 1500 g at birth, average GV increased and the percentage with postnatal growth failure decreased. However, in 2013, half of these infants still demonstrated postnatal growth failure and one-quarter demonstrated severe postnatal growth failure.