Children's Health

Increasing nutritional intake, especially protein, among extremely premature infants in the NICU could improve their growth rate

Achieving adequate growth in extremely premature infants being cared for in neonatal intensive care units (NICUs) is very difficult, but it is critical for their later growth and cognitive development. Unfortunately, 97 percent of infants who weigh less than 3.3 pounds at birth are discharged weighing less than the 10th percentile for corrected gestational age (GA). The nutritional intake of these vulnerable premature infants in many NICUs could be improved, according to a study supported in part by the Agency for Healthcare Research and Quality (HS07015). The researchers, who were led by Douglas K. Richardson, M.D., M.B.A., of the Harvard School of Public Health, examined the weight growth velocity of 564 extremely premature infants at six NICUs who were less than 30 weeks' GA at birth and stayed in the NICU at least 16 days.

The researchers used case mix (for example, GA, race, and illness severity), exposure to medical practices/complications (for example, respiratory support, postnatal steroids for lung support, and infection), and nutritional intake (kcal/kg/day and protein in g/kg/day) to predict weight growth velocity between day 3 and day 28 (or discharge, if transferred early). Weight growth velocities varied significantly among the six NICUs. However, none of the NICUs provided infants (on average) with the recommended levels of nutrition with respect to calories and protein (ideally 130-150 kcal/kg/day and 3.5-4 g protein/kg/day), and only one NICU approximated intrauterine growth standards of 15 g/kg/day.

Adjustment for case mix and medical factors explained little of this variability, but additional control for calorie and especially protein intake accounted for much of the variability among NICUs. For the average infant, adjusted growth velocity ranged from 10.4 to 14.3 g/kg/day among the sites studied. The model predicted that adding 1 g/kg/day of protein to the mean intake for this sample would increase growth by 4.1 g/kg/day.

See "Intersite differences in weight growth velocity of extremely premature infants," by Irene E. Olsen, Ph.D., R.D., Dr. Richardson, Christopher H. Schmid, Ph.D., and others, in the December 2002 Pediatrics 110(6), pp. 1125-1132.

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