Predictors and consequences of in-hospital formula supplementation for healthy breastfeeding newborns.

BACKGROUND Although exclusive breastfeeding is recommended for the first 6 months, the use of breast milk substitutes is widespread around the world. OBJECTIVES To describe the patterns of infant formula supplementation among healthy breastfeeding newborns, to identify factors contributing to in-hospital formula supplementation, and to assess the dose-response relationship between the amount of in-hospital formula supplementation and the duration of any breastfeeding. METHODS A sample of 1246 breastfeeding mother-infant pairs was recruited from 4 public hospitals in Hong Kong and followed prospectively for 12 months or until weaned. Multiple logistic regression analysis was used to examine factors associated with in-hospital supplementation. Cox regression analysis was used to explore the impact of in-hospital supplementation on breastfeeding duration. RESULTS Of the total, 82.5% of newborns were supplemented in the hospital; one-half received formula within 5 hours of birth. Assisted vaginal delivery (odds ratio [OR] = 2.06, 95% confidence interval [CI] 1.03, 4.15), cesarean section (OR = 3.45, 95% CI 1.75, 6.80), and higher birth weight (OR = 1.56, 95% CI 1.12, 2.18) were positively associated with in-hospital formula supplementation, whereas initiating breastfeeding in the delivery room (OR = 0.55, 95% CI 0.33, 0.89) was associated with decreased likelihood of in-hospital supplementation. Any infant formula in the first 48 hours was associated with a shorter duration of breastfeeding (hazard ratio [HR] = 1.51, 95% CI 1.27, 1.80), but there was no dose-response effect. CONCLUSION In-hospital formula supplementation is common in Hong Kong hospitals and appears to be detrimental to breastfeeding duration. Continued efforts should be made to avoid the provision of infant formula to breastfeeding babies while in the hospital unless medically indicated.