Level 2 [mid-level] evidence

Exclusive breastfeeding — except for vitamins, minerals, and medications — for the first 6 months of life is recommended by several health organizations. However, before abundant maternal milk production is established, some exclusively breastfed newborns may have an increased risk of hyperbilirubinemia and dehydration. Supplementation during early life is discouraged due to concerns that it may alter intestinal microbiota and have a negative impact on continued breastfeeding.

In a recent trial, 164 healthy singleton infants born ≥37 weeks’ gestation (age range, 24 to 72 hours) who were exclusively breastfed and had pronounced weight loss (≥75th percentile for age) were randomly assigned to limited formula supplementation vs continuation with exclusive breastfeeding. Supplementation consisted of giving the newborn 10 mL of formula via a feeding syringe after each breastfeeding; supplementation was discontinued after abundant maternal milk production was established. Breastfeeding status was assessed via telephone interview conducted by an outcome assessor blinded to treatment allocation. 

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Newborns in the supplementation group received formula on an average of 5.4 times per day for a median of 2 days, and 37% of newborns in the control group had been given some formula by 1 week of age. There were no significant differences in the rates of breastfeeding at 1 month (86.5% with supplementation vs 89.7% with exclusive breastfeeding, risk ratio for cessation 1.21; 95% CI, 0.55-3.16) or rates of breastfeeding without formula use in the previous 24 hours (54.6% vs 65.8%). None of the newborns in the supplementation group were readmitted to the hospital, while 5 newborns (4.8%) in the control group were (P =.06). The reasons for readmission in the control group were hyperbilirubinemia in 3, umbilical infection in 1, and unknown in 1.

The findings of this trial suggest that early limited formula supplementation of breastfeeding does not significantly reduce rates of continued breastfeeding at 1 month. The confidence in this finding is tempered by the wide 95% confidence interval in risk of breastfeeding cessation, which includes the possibilities of both beneficial and adverse clinically significant differences. It should be noted that supplementation was given via a feeding syringe rather than a bottle, and this may have helped to avoid nipple confusion, which may interfere with breastfeeding in some infants.

A possible benefit of early supplementation in these neonates was suggested by the reduced rate of hospital readmissions, but this difference did not reach statistical significance. Preliminary analyses of intestinal microbiota conducted on 15 convenience stool samples taken during the trial were promising in that they suggest that the limited use of formula may not reduce the abundance of Lactobacillus or increase the abundance of Clostridia. These findings, however, require further investigation. Finally, the generalizability of the findings is limited by the low representation of women younger than 25 years of age (<15%), a population at increased risk of early discontinuation from breastfeeding.

In summary, this trial suggests that temporary and limited syringe-administered formula supplementation until an abundant maternal milk supply is established may be considered for selected neonates and their mothers.

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Alan Ehrlich, MD, is a deputy editor for DynaMed, Ipswich, Massachusetts, and assistant clinical professor in family medicine, University of Massachusetts Medical School, Worcester.

DynaMed is a database that provides evidence-based information on more than 3000 clinical topics and is updated daily through systematic surveillance covering more than 500 journals.


Flaherman VJ, Narayan NR, Hartigan-O’Connor D, Cabana MD, McCulloch CE, Paul IM. The effect of early limited formula on breastfeeding, readmission, and intestinal microbiota: a randomized clinical trial. J Pediatr. 2018;196:84-90.