Study looks at in-hospital weight loss of newborns

Healthy, full-term newborn babies tend to lose weight during the first few days after their birth. A groundbreaking new study published in the latest issue of the Journal of Human Lactation explores the reasons why certain newborns lose more (or less) than others and what conclusions can be drawn from the research.

The purpose of the study, published by SAGE in the Journal of Human Lactation, for the International Lactation Consultant Association, was to determine the factors associated with in-hospital weight loss of healthy, full-term newborns, including birth and infant-feeding factors as well as maternal and newborn demographics.

The study found a substantial difference in weight loss between exclusively breastfed and completely formula-fed newborns, which lost less. That disparity led the researchers to conjecture that formula-fed infants may be at risk of early overfeeding. Supplemented breastfed infants had similar weight loss patterns to the exclusively breastfed newborns.

"Degree of weight loss is critical in the decision to supplement breastfed infants with formula," write the study's authors, Patricia J. Martens, IBCLC, PhD, and Linda Romphf, IBCLC. "However, given the overhydration of newborns, the early loss of meconium, and small fluid intake in the first few days, loss of 5-7% of birth weight is considered physiologically appropriate."

Newborn feeding experiences may be critical in metabolic imprinting and may factor into adult weight. "The most influential predictor of weight loss in newborns is the type of infant feeding," conclude the authors. "Further study is critical, especially in light of current research on the association between early weight gain of formula-fed infants and adult obesity. Breastfeeding-supportive environments are necessary to support and enable women to breastfeed."