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The Effects of Prescribed Versus Ad Libitum Feedings and Formula Caloric Density on Premature Infant Dietary Intake and Weight Gain

Pridham, Karen; Kosorok, Michael R.; Greer, Frank; Carey, Patrick; Kayata, Sahar; Sondel, Sherie


Background: Although feedings that are organized on an ad lib basis (i.e., in response to infant cues of hunger and of satiation) could enhance an infant's self-regulatory capacities for feeding, ad lib feeding of fully nipple-fed premature infants in a special care nursery has not been examined.

Objective: To study whether the caloric and protein intake and weight change of fully nipple-fed preterm infants differed by the feeding regimen (prescribed or ad lib) and by the caloric density of the formula (20- or 24-kcalories per ounce).

Method: The 78 infants who participated in the study were randomized to prescribed or ad lib feeding regimens and, within each regimen, were further randomized to receive either 20-calorie or 24-kcalorie per ounce formula. Dietary intake (volume/kg, caloric intake/kg) and weight change (grams/kg gained 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 density on dietary intake and weight change, controlling biologic variables (infant gender, race, lung disease diagnosis, treatment with supplemental oxygen, gestational age and weight at birth, and weight on the day prior to full nipple-feeding).

Results: Overall, the ad lib feeding regimen had a negative effect on volume intake and caloric intake. Weight gain was influenced by caloric intake, but not by feeding regimen or the caloric density of the diet. With increased full nipple-feeding experience, caloric intake of ad lib feeders approached that of the infants fed on the prescribed regimen.

Conclusions: Development of self-regulatory capacities through ad lib feeding experience was indicated by infant regulation of the volume of intake by the caloric density of the formula, an unexpected finding. Furthermore, the approach of the caloric intake of infants on the ad lib regimen to that of infants on the prescribed regimen suggests they had gained skill in regulating intake with experience. Whether or not the trend for similar intakes would continue beyond 5 days is a question for further study.

*Karen Pridham, PhD, RN, is a Professor Emerita, School of Nursing.

*Michael R. Kosorok, PhD, is an Associate Professor, Department of Biostatistics.

*Frank Greer, MD, is a Professor, Department of Pediatrics.

*Patrick Carey, MS, was a biostatistician with the Department of Biostatistics at the time this article was written.

Sahar Kayata, MD, is a neonatologist, Sinai-Samaritan Medical Center, Milwaukee, WI.

*Sherie Sondel, MeD, RN, is Associate Director, Pediatric Pulmonary Center, Department of Pediatrics.

*From the University of Wisconsin-Madison, Madison, WI.

Accepted for publication December 1, 1997.

Supported by the National Institute of Nursing Research Grant R01-NR02875-01 and by National Institutes of Health Grant No. M01 RR031 86 from the National Center for Research Resources to the University of Wisconsin Medical School.

Special appreciation is extended to Audrey Chang, PhD, for her extensive contributions to the design of the study. Thanks are extended to the nursing and medical staffs of the Sinai-Samaritan Medical Center Convalescent Nursery in Milwaukee, WI, and specifically to Patricia Weber, RN; Dale Nees, RN, MBA; Bonnie Behee-Semler, RN, MEd; Cyndee Dubisch, RN, BSN; TiAnne Kram, RN, BSN; Shirley Pilak-Stachowiak, RN, BSN; Sandra Schaefer, RN; Gail Bagwell, RN, MS; Marilu Retzer, RN, BSN; and Kathy Hoof.

Address reprint requests to Karen Pridham, PhD, RN, University of Wisconsin-Madison, School of Nursing, 600 Highland Ave., Madison, WI, 53792

© 1999 Lippincott Williams & Wilkins, Inc.