The effects of prescribed versus ad libitum feedings and formula caloric density on premature infant dietary intake and weight gain

Background: Although feedings that are organized on an ad rib basis (i.e., in response to infant cues of hunger and of satiation) could enhance an inf ant's self-regulatory capacities for feeding, ad lib feeding of fully nippl e-fed premature I infants in a special care nursery has not been examined. Objective: To study whether the caloric and protein intake and weight chang e of fully nipple-fed preterm infants differed by the feeding regimen (pres cribed or ad lib) and by the caloric density of the formula (20- or 24-kcal ories per ounce). Method: The 78 infants who participated in the study were randomized to pre scribed or ad lib feeding regimens and. within each regimen, were further r andomized to receive either 20-calorie or 24-kcalorie per ounce formula. Di etary intake (volume/kg, caloric intake/kg) and weight change (grams/kg gai ned or lost) were assessed for each of the 5 study days. Multivariate data analysis was used to examine the effects of feeding regimen and caloric den sity on dietary intake and weight change, controlling biologic variables (i nfant gender, race, lung disease diagnosis, treatment with supplemental oxy gen, gestational age and weight at birth, and weight on the day prior to fu ll nipple-feeding). Results: Overall, the ad lib feeding regimen had a negative effect on volum e intake and caloric intake. Weight gain was influenced by caloric intake, but not by feeding regimen or the caloric density of the diet. With increas ed full nipple-feeding experience, caloric intake of ad lib feeders approac hed that of the infants fed on the prescribed regimen.. Conclusions: Development of self-regulatory capacities through ad lib feedi ng experience was indicated by infant regulation of the Volume of intake by the caloric density of the formula, an unexpected finding. Furthermore, th e approach of the caloric intake of infants on the ad lib regimen to that o f infants on the prescribed regimen suggests they had gained skill in regul ating intake with experience. Whether or not the trend for similar intakes would continue beyond 5 days is a question for further study.