Baby Bottle Size and Intake: Is There a Link?

William T. Basco, Jr., MD, MS


May 31, 2016

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

Wood CT, Skinner AC, Yin HS, et al
Acad Pediatr. 2016;16:254-259

Study Summary

Rapid weight gain in the first year of life correlates with later risk for obesity. Studies in adults and older children have demonstrated that food and beverage container size correlates with the amount consumed, raising the concern that bottle size affects feeding volumes in non-breastfed infants. This study involved analysis of the correlation between bottle size used and average volume consumed among 2-month-old infants who had been enrolled in a previous cohort study. The data were collected at four sites in the United States from 2009 to 2014. The infants were enrolled at the 2-month visit. Only formula-fed infants (n = 278) were enrolled; infants who received any amount of breastmilk were excluded.

Average daily formula consumption was calculated on the basis of parental report of the number of feedings in a 24-hour period, how much formula the parent usually gave the child at each feeding, and what type of bottle was used. For the analysis, bottles were divided into those that held fewer than 6 oz, and 6 oz or more. Adjustment variables included infant birth weight, sex, age at enrollment, race/ethnicity of the caregivers, a measure of household income, and whether the children and families were involved in the supplemental nutrition program for women, infants, and children (WIC).

Slightly more than half of the caregivers (54%) used the smaller bottles. The mean number of daily feedings was 7.3, with a mean volume of 4.4 oz. However, both the number of daily feedings and the volume of the feeding had a tremendous range, with the largest feeding volume topping out at 10 oz. The median daily total volume was 30 oz. Infant age and birth weight were positively correlated with using a larger bottle, whereas Hispanic ethnicity was associated with lower odds of using the larger bottle sizes. As bottle size increased, the daily volume consumed also increased. In bivariate analyses, income, number of children in the home, sex, and enrollment in WIC were not associated with bottle size.

In the adjusted model, larger bottle use was associated with a daily formula intake that was approximately 4 oz more. Depending on the child's weight, those extra 4 oz daily would translate to 5%-20% extra calories per child. The authors commented that their findings represent association, not causation, and in fact, older and larger infants may require more formula to reach satiety, prompting the association with larger bottle sizes. They concluded that further research is required to determine directionality of these associations.


This study examined a fairly simple question, but many potential hypotheses could explain the findings. Using large food-serving vessels (in this case, bottles) may encourage increased nutrient intake. The findings have face validity, given what is known about the amount of food or beverage consumed when older children or adults are presented with larger portions. Many of us typically ask caregivers about the volume delivered when assessing the adequacy of infants' intake, but I imagine that the proportion who ask about bottle size is much smaller. For now, I'm content to remain concerned about the possible association and will ask more often about bottle size when a parent reports what seems to be an unbelievable volume intake or when I am concerned about an infant's weight.



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