Importance: The capacity for regulation of energy intake (REI) to match energy needs is thought to contribute to differences in weight gain, and preventing excess infant weight gain is a priority.
Objective: To determine capacity for REI across infancy.
Design, setting, and participants: For this cohort study, a convenience sample of mother-infant dyads was recruited from the community in Michigan between 2015 and 2019. Inclusion criteria were healthy, full-term infants with weight appropriate for gestational age; biological mothers who were 18 years or older, English speaking, and a legal and custodial guardian; and infant having had consumed 2 oz or more in 1 feeding from an artificial nipple at least once per week. Infants were followed in the home setting with staff support for up to 12 months.
Interventions: Mother-infant dyads participated at infant age 1, 2.5, 5, 7, 10, and 12 months. In the intervention condition, mothers offered a feeding every hour for 6 hours. In the control condition, mothers fed infants as they typically would for 6 hours. Intake was recorded and kilocalories calculated.
Main outcomes and measures: Capacity for REI was indexed as the difference in intake in kilocalories per kilogram of body weight (intervention minus control condition); a value of 0 indicated perfect REI. Maternal and infant characteristics were obtained by questionnaire, and anthropometry was measured. Using multiple imputation, the intercept and slope for difference in kilocalories per kilogram across the 6 age points were estimated using mixed models accounting for repeated measures within participants. Statistical analyses were conducted between September 2021 and February 2023.
Results: The sample included 175 infants (87 [49.71%] female, 88 [50.29%] male; 494 pairs of intervention and control conditions and 4630 feedings). The mean (SD) 12-month weight-for-age z score was 0.1 (0.8). Mean (SD) gestational age as 39.55 (1.05) weeks, and mean (SD) birth weight was 3.43 (0.41) kg. Mean (SD) breastfeeding duration for those who reported stopping by 12 months was 17.83 (12.03) weeks. As designed, the intervention (compared with control) condition included more feedings at shorter intervals. After collapsing the data across age points in a mixed model accounting for repeated measures within participants, the REI estimate at 1 month differed from 0. On average, infants ate 5.21 kcal/kg (95% CI, 2.89-7.54 kcal/kg) more in the frequent feeding intervention condition than in the ad lib feeding control condition. This difference did not significantly change over 12 months of infancy (REI slope = -0.01 kcal/kg per month; 95% CI, -0.02 to 0.03 kcal/kg per month).
Conclusions and relevance: The study's findings suggested that, on average, when offered more frequent feedings, healthy, full-term infants may overeat. The results provide support for responsive feeding as a strategy for preventing excess infant weight gain.