570 - Caloric Exposure and Growth in Infants Enrolled in the NICHD NRN Milk Trial: A Secondary Analysis

Publication Number: 570.4465

Samuel Gentle, Yale School of Medicine, Guilford, CT, United States; Ariel A.. Salas, University of Alabama School of Medicine, Birmingham, AL, United States; Jane E. Brumbaugh, Mayo Clinic, Rochester, MN, United States; Brenda Poindexter, Children's Healthcare of Atlanta, Atlanta, GA, United States; Seabrook Jeffcoat, University of Alabama at Birmingham, Birmingham, AL, United States; Waldemar Carlo, UAB School of Medicine, Birmingham, AL, United States; Tarah Colaizy, University of Iowa Stead Family Children's Hospital, Iowa City, IA, United States

Background: Whereas provision of mother’s own milk is the optimal nutritional strategy in preterm infants, alternative nutritive strategies are required for neonates for whom provision of mother’s own milk is not feasible. In the NICHD Milk Trial, donor milk exposed infants experienced slower weight gain than formula fed infants but data on the caloric density targets throughout hospitalization were not reported.

Objective: To determine whether a subgroup of infants in the NICHD MILK Trial randomized to donor milk: (1) were exposed to lower caloric densities for a higher proportion of study days as compared to infants randomized to the formula group and (2) experienced slower weight gain in part from differences in caloric exposures.

Design/Methods: This was a secondary analysis of the NICHD NRN MILK Trial which randomized 483 infants ( < 29 weeks’ gestation or < 1000 g within the first 21 postnatal days) to receive either donor milk (N=239) or preterm formula (N=243). Data from 168 infants (35%) were available for the analysis. Infants’ initial study diet was either unfortified donor milk or 24 cal/oz preterm formula. Subsequent goal caloric densities were planned to be similar until growth faltering or excessive growth were noted. The duration of caloric exposures were compared between randomization groups from which the proportional contribution of each caloric exposure to an infant’s study diet was determined. A test for interaction was then performed between discharge anthropometric z-scores and caloric exposure as an effect modifier.

Results: Among the 168 analyzed, 85 infants were randomized to donor milk and 83 infants were randomized to preterm formula. The median gestational age was 26w (IQR 25-27) in both the donor milk group and formula group (Table 1). Infants received the study diet for a median of 56 to 57 days. Donor milk infants had a lower discharge weight z-score compared to infants in the formula group (median -1.8 vs -1.2; p=0.002). Donor milk infants were exposed to 24 kcal/oz formulation for fewer days compared to formula fed infants (mean 13 vs 19; p=0.01)(Table 2). A test for interaction between caloric exposure and discharge z-scores was nonsignificant for both weight (p=0.51) and length (0.80)(Figure 1).

Conclusion(s): In this subgroup of infants enrolled in the NICHD NRN MILK Trial, caloric exposures cannot account for growth faltering in infants randomized to donor milk. If substantiated by the remaining data from the trial, alternative nutritional strategies may be needed for infants fed donor milk to prevent growth failure.

Table 1: Baseline and Clinical Characteristics of the Study Population
PAS_MILK_Table 1.pdf

Table 2: Anthropometric and Study Diet Characteristics
PAS_MILK_Table 2.pdf

Caloric Exposure and Discharge Weight
Fig1.pdfFigure 1. Linear relationships between the proportion of study days infants were exposed to >27 kcal/oz and discharge weight (Panel A) and length (Panel B) z-score.