Postdischarge nutrition of preterm infants: more questions than answers.

Postnatal growth retardation is inevitable in preterm infants, the more immature the infant the greater the degree of postnatal growth retardation at hospital discharge. After hospital discharge, several studies have shown that growth is poorer in preterm infants fed a standard term formula than those fed a nutrient-enriched infant formula. This is not surprising because term formulas are designed to meet the requirements of the term infant, not the more rapidly growing preterm infant. After hospital discharge, breastfed infants do not grow as well as their formula-fed counterparts. Yet, there are no randomized controlled trials comparing growth in breastfed infants who did and did not receive nutrient supplementation. If mature human milk is designed to meet the needs of the term infant then breastfed preterm infants may also benefit from nutrient supplementation. Questions persist about nutritional support of preterm infants after discharge. What is the ideal composition of a postdischarge formula? Given the wide heterogeneity in nutritional status of preterm infants at hospital discharge and the difference in growth rates and composition between girls and boys, it is not clear that one formula can or will meet the nutritional needs of all infants. Studies in which infants were fed a nutrient-enriched formula to >/=6 months' corrected age show the most consistent advantage while those in which the nutrient-enriched formula was fed to </=2 months' corrected age had no effect on growth. Whether this is a reflection of the duration of feeding or not is unclear. Further studies are needed to examine this issue. To date, little attention has focused on the role and/or effects of complimentary feeds these infants. Complimentary feeds will confound the effects of any study examining postdischarge growth in preterm infants. However, they may also be an important adjunct in meeting nutritional needs of these high-risk infants. Further studies are also needed to examine this issue.