Most low birth weight infants (BW<1500g) weigh less than the 10th percentile of intrauterine standards at hospital discharge. Many remain small and have neurodevelopmental deficits. Studies have shown that giving higher protein and energy intakes during hospitalization improves growth but does not completely abolish the usual growth deficit. More recently post discharge formulas with somewhat more protein than standard formulas have been introduced but these do not support greater growth beyond 2 to 4 months post term. The enhanced growth response to protein and energy during early vs. later life suggests that there is a finite period during which the infant can maximally use high nutrient intakes for growth. This concept, supported by studies in animals, has not been studied systematically in infants. If true, higher protein intake during this finite period should reduce short- and long-term growth deficits and also improve neurodevelopmental outcome.

There is a finite as yet undefined period in early life during which LBW infants use dietary protein most efficiently for growth and maximizing protein intake during this period will improve short term growth and reduce long term growth as well as neurodevelopmental deficits.

Random assignment of formula-fed infants to formulas differing only in protein content plus a breast-fed reference group. 13C-Leu oxidation before discharge, term, 2 and 4 mo post-term. Anthropometry and body composition through 18 months of age and neurodevelopmental assessment at 18 months of age.

80/group = 240 over 4 years (160 formula-fed; 80 breast-fed)

LBW infants (BW <1750g), formula-fed or breast-fed. Since this study is non-invasive, infants can participate in other studies concurrently provided the other studies do not interfere with protein utilization.

To date, 117 subjects have been enrolled, 20 have completed the entire study through 18 mos and 60 remain active.

Since the last renewal, 48 subjects have been enrolled, 9 of whom withdrew or were withdrawn. No adverse events were encountered during this period.