Estimating the Impact of In-Hospital Infant Formula Supplementation on Breastfeeding Success

Abstract

Objective:

To assess whether in-hospital infant formula supplementation impacts later successful breastfeeding among healthy mother–infant dyads in the United States who are not intending to exclusively use infant formula.

Study Design:

Using secondary analysis of a national longitudinal survey (Infant Feeding Practices Study II, n = 2,399), we estimated effects of in-hospital infant formula supplementation on later breastfeeding success by matching mothers whose infants received in-hospital formula supplementation with mothers whose infants did not. Estimates were compared across four matching methods. Outcomes of breastfeeding success included likelihood of following a sustained breastfeeding trajectory for the first year postpartum; feelings of favorability and breastfeeding as long as desired postweaning; and breastfeeding intention, initiation, and duration for subsequent children.

Results:

In-hospital formula supplementation halved the likelihood of following a breastfeeding trajectory characterized by sustained exclusive breastfeeding. Supplementation decreased feelings of favorability toward breastfeeding postweaning but did not impact the likelihood of feeling that one breastfed as long as desired. Supplementation did not impact intention to breastfeed a future child; it did, however, decrease the likelihood of breastfeeding initiation with a subsequent child by >66% and reduced average duration of breastfeeding any subsequent children by >6 weeks.

Conclusion:

A lack of experimental methodologies in previous studies makes it difficult to determine a causal link between infant formula in the hospital and less breastfeeding success. Assuming we have accounted for all appropriate confounders, this study provides evidence for such a causal link. Birth hospital policies and practices should speak of this risk of harm.