Comparing Alternative Breast Milk Feeding Questions to U.S. Breastfeeding Surveillance Questions

Background: Most mothers in the United States express their milk, which is then bottle fed to their infants. The National Immunization Survey (NIS), used to report national breastfeeding prevalence, asks about infant breast milk consumption, regardless of whether it is consumed at the mother's breast or from a bottle. The NIS data are often erroneously interpreted, however, to mean prevalence of at-the-breast feeding. We hypothesized that over half of infants classified as breastfed at 3, 6, and 12 months by the NIS questions would also be consuming expressed breast milk. Materials and Methods: A convenience sample of 456 mothers of infants 19-35 months of age recruited through ResearchMatch.org completed an online infant-feeding questionnaire. The questionnaire included both the NIS questions and more-detailed questions about feeding mode, distinguishing between at-the-breast and bottle. Results: Based on responses of our sample to the NIS questions, it could be interpreted that 74%, 64%, and 39% of mother-infant dyads were at-the-breast feeding at 3, 6, and 12 months, respectively. However, at each time point, most infants consumed at least some breast milk from a bottle. As infants got older, the proportion of breast milk consumed from a bottle increased. Conclusions: In this U.S. sample, the predominant breast milk feeding style involves both at-the-breast and expressed breast milk feeding. Future research and national surveillance should consider including separate measures of maternal breast milk expression and infant consumption of expressed breast milk to enable meaningful exploration of maternal and infant outcomes associated with these asynchronous behaviors.