Association Between Bottle Size and Formula Intake in 2-Month-Old Infants

To determine range of bottle sizes used and examine the relationship between bottle size and total daily consumption of infant formula.

Cross-sectional analysis of baseline data collected as part of Greenlight, a cluster randomized trial to prevent childhood obesity at 4 pediatric resident clinics. The Greenlight study included healthy, term infants. For our analysis, parents of exclusively formula-fed infants reported volume per feed, number of feeds per day, and bottle size, which was dichotomized into small (<6 oz) or large (≥6 oz). We identified determinants of bottle size, and then examined relationships between bottle size and volume fed with log-transformed ordinary least squares regression, adjusting for infant age, sex, birth weight, current weight, race/ethnicity, and enrollment in Special Supplemental Nutrition Program for Women, Infants, and Children.

Of 865 participants in the Greenlight study, 44% (n = 378; 21.8% white, 40.6% black, 35.3% Hispanic, 2.4% other) of infants were exclusively formula fed at 2 months. Median volume per day was 30 oz (interquartile range 12), and 46.0% of infants were fed with large bottles. Adjusted for covariates, parents using larger bottles reported feeding 4 oz more formula per day (34.2 oz, 95% confidence interval 33.5-34.9 vs 29.7 oz, 95% confidence interval 29.2-30.3, P = .03).

Among exclusively formula-fed infants, use of a larger bottle is associated with parental report of more formula intake compared to infants fed with smaller bottles. If infants fed with larger bottles receive more formula, these infants may be overfed and consequently at risk for obesity.