Objective: Early exposure to formula can interfere with successful long-term breastfeeding. The objective of this study was to determine whether limiting the volume of formula used in the first month attenuates formula's detrimental impact on long-term breastfeeding success. Materials and Methods: Using detailed data on dietary intake from a randomized clinical trial, we conducted a secondary analysis of the association between volume of formula received in the first month and breastfeeding cessation before 6 and 12 months of age. We used descriptive statistics and multivariable logistic regression, respectively, to explore this association without and with adjustment for demographic and clinical predictors of infant feeding. Results: Among 199 breastfeeding infants, 80 (40%) received formula daily at 1 month of age, and breastfeeding cessation before 6 and 12 months of age was higher for these infants (46% and 67%) than for those breastfed exclusively (6% and 27%) (p < 0.0005 for each). The risk of cessation did not differ between those who received ≤4 fl oz daily in the first month (11%) and those who did not receive formula in the first month (6%) (p = 0.42). Adjusting for gestational age, race/ethnicity, income, and intention to breastfeed exclusively, the odds ratio for the outcome of cessation before 6 months was 1.15 (95% confidence interval = 0.20-6.67) for infants who received ≤4 fl oz daily compared with those who breastfed exclusively. Conclusion: Limiting formula volumes to ≤4 fl oz daily may attenuate the deleterious association between early formula use and subsequent successful breastfeeding.
Keywords: breastfeeding; infant formula; newborn.