Adding Formula May Not Sway Baby from Breast

Limited Supplementation May Not Impact Infant Gut Bacteria; May Reduce Hospital Readmissions

By Suzanne Leigh

Baby holding feedFor infant nutrition, breast-is-best is common advice. Now, a study led by researchers at UCSF has demonstrated a seemingly contradictory way for newborns losing more weight than most to breastfeed in the longer term: add a little formula for a couple of days.

For infants in this study, offering formula after each breastfeeding for an average of two days did not stop new mothers from continuing to breastfeed, nor did it have a detrimental impact on the bacteria lining the infant’s intestines, the authors concluded in the study publishing in The Journal of Pediatrics on March 14, 2018.

The study may appear to contradict the advice of some experts who warn that formula exposure in breastfed babies results in weaning.

Researchers from UCSF, UC Davis and Penn State College of Medicine tracked the feeding habits of 164 exclusively breastfed newborns, aged between 1 to 3 days old, whose weight loss was in the 75th percentile or above for age. Half of the mothers added syringe-fed formula after each breastfeeding, which was stopped when the mother’s mature milk came in at two-to-five days after delivery. The other half continued to breastfeed exclusively. 

Researchers found that at 1 week of age, 69 of 72 babies (95.8 percent) who had received supplementary formula were still breastfeeding, versus 73 of 78 babies (93.6 percent) who were not supplemented. At 1 month of age, a similar number of babies in both cohorts were continuing to breastfeed: 86.5 percent in the supplemented group and 89.7 percent in the non-supplemented group. 

Study May Suggest Docs Are Due for Guidelines Review 

“Our research shows that in healthy newborns with pronounced weight loss, adding formula for a limited period did not interfere with breastfeeding,” said first author Valerie Flaherman, MD, an attending pediatrician at UCSF Benioff Children’s Hospital San Francisco and principal investigator for the study. “These results indicate that it may be time for guidelines to include specific guidance about which infants may benefit from supplementation until the mother’s milk comes in.”

Current guidelines from the American Academy of Pediatrics, the World Health Organization’s Baby-Friendly Hospital Initiative and the Joint Commission recommend exclusive breastfeeding for the first six months of life and discourage supplementation for breastfed newborns. 

The researchers also analyzed stool samples from eight newborns in the supplemented group and seven in the non-supplemented group, and compared them for gut bacteria.

“Some evidence suggests that using formula along with breastfeeding may reduce beneficial bacteria and increase harmful bacteria in infants,” said Flaherman, who is also associate professor in the UCSF departments of Pediatrics and of Epidemiology and Biostatistics.

However, the researchers found no differences between the two groups in the amount of Lactobacillus and Clostridia, bacteria associated with infectious and allergic conditions. 

Readmissions Lower for Babies on Formula Boost 

A further bonus was that the supplemented babies may be less likely to be readmitted to the hospital by 1 month of age for hyperbilirubinemia, a condition that leads to jaundice in newborns and is sometimes caused by inadequate nutrition. Of the four infants readmitted for this condition, three of them were in the non-supplemented group. 

“Rates of exclusive breastfeeding have risen substantially in U.S. hospitals,” said Flaherman. “While exclusive breastfeeding has long-term benefit, it also causes increased risk of hyperbilirubinemia, dehydration and readmission in first few days. The targeted use of a limited volume of syringe-fed formula may provide the best of both worlds – improved hydration in the first few days, with sustained breastfeeding over the first month.

“Our study suggests that by offering a limited volume of syringe-fed formula until the onset of mature milk production, mothers were able to continue to breastfeed. Keeping the formula use limited and temporary may preclude any lasting impact on intestinal bacteria.”

Funding for the study was provided by the Healthcare Resources and Service Administration Maternal Child Health Bureau. The senior author is Ian M. Paul, MD, of Penn State College of Medicine in Hershey. Co-authors are Michael Cabana, MD, and Charles McCulloch, PhD, of UCSF; and Nicole Narayan, PhD, and Dennis Hartigan O’Connor, MD, PhD, of UC Davis. Co-author Cabana has served as a paid consultant for Nestle for his work on probiotics. No further conflicts of interest have been disclosed. 

UC San Francisco (UCSF) is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. It includes top ranked graduate schools of dentistry, medicine, nursing and pharmacy; a graduate division with nationally renowned programs in basic, biomedical, transitional and population sciences; and a preeminent biomedical research enterprise. It also includes UCSF Health, which comprises three top-ranked hospitals, UCSF Medical Center and UCSF Benioff Children's Hospitals in San Francisco and Oakland, and other partner and affiliated hospitals and healthcare providers throughout the Bay Area. Please visit