Early Life Milk Intake Among Infants of Different Feeding Modes
Authors: Davis Erin , Donovan Sharon M. , Dong Ping 
Published: November 2023

Feeding mode is known to impact an infant's growth pattern throughout the first year of life, which can be an important factor in the risk of childhood obesity. While breastfeeding has been shown to be protective against later overweight and obesity, the underlying mechanisms involved remain unclear. Feeding practices of young infants are hard to measure, but may provide valuable information for clinicians and researchers studying the long‐term implications of early life growth trajectories. It is hypothesized that feeding mode affects self‐regulation and infant satiety; however, few studies have investigated whether intake characteristics differ among infants who are exclusively breastfed (EBF), mixed‐fed (MF), or exclusively formula‐fed (EFF). The objective was to assess whether feeding frequency, average intake per feeding, and overall daily intake differ among infants of different feeding regimes, and whether these characteristics may be related to the infant's weight‐for‐length (WFL) Z‐score and maternal BMI. Intake data was collected for 191 healthy, 6‐week old infants, enrolled in the STRONG Kids 2 cohort at the University of Illinois at Urbana‐Champaign. Mothers weighed infants, before and after each feeding, over an average of 23.38 ± 2.26 hours, in order to measure intake volume. Feeding mode was assessed from a questionnaire completed by the mother. The overall intake weight (ml/kg BW) consumed across the entire weighing period was not significantly different between the 3 feeding methods. Average intake per feeding, across all feeding modes, was positively associated with overall ml/kg intake (P<0.0001) and negatively associated with feeding frequency (P<0.0001). Feeding frequency tended to differ by feeding mode (P=0.056). EBF infants (n = 151) fed on average 9.17 ± 1.87 times across the entire weighing period, which was significantly greater than the number of feeds of 7.92 ± 1.31 recorded for the EFF infants (n = 12). The feeding frequency of MF infants (n = 28) did not differ from that of EBF or EFF infants. Average intake per feeding was significantly higher among EFF infants (102.2 ± 34.0) compared to both EBF infants (84.4 ± 25.5) and MF infants (74.8 ± 29.4), which did not differ from each other. Further analysis was completed to evaluate differences among 132 EBF infants based on whether or not mothers indicated regular breast milk pumping. While the overall intake (ml/kg) and total number of feeds per day did not differ among the two groups of EBF infants, average intake per feeding tended to be greater (P=0.06) in infants whose mothers regularly pump breast milk. While none of the reported feeding characteristics were associated with infant WFL Z‐score, feeding frequency was negatively associated with maternal BMI at 6 weeks postpartum. Average intake per feeding and overall intake (ml/kg) were not associated with maternal BMI. These findings suggest that intake characteristics of infants differ based on feeding mode and may provide context regarding differences in growth trajectories observed during later infancy.

Support or Funding Information

Supported by the National Dairy Council (NDC).