The study, published online today in the journal Pediatrics, found a high proportion of breastfed newborns who received little or no supplemental formula lost an excessive amount of weight. Normally, newborns are expected to lose up to 10 percent of their birth weight in the first days of life. But nearly eighteen percent, nearly one in five, of these infants lost more than 10 percent of their birth weight.
“Under usual circumstances, excess weight loss is considered abnormal and can increase the risk to the infant of problems such as jaundice and re-hospitalization. Babies who lose an excessive amount of weight may need to be supplemented with formula,” said Caroline Chantry, professor of pediatrics in the UC Davis School of Medicine and an internationally recognized breastfeeding expert. Typically, infants lose excess weight because they are feeding poorly or the mother has delayed onset of breast milk production.
However, the findings of the study suggest that some of the infants’ weight loss may be unrelated to feeding. “[A] particularly noteworthy finding is that the prevalence of excessive weight loss was significantly related to maternal intra-partum fluid balance,” the study said. ” [The rate] of excessive weight loss more than tripled when positive maternal fluid balance exceeded 200 milliliters per hour” during labor and delivery, the study found.
“We don’t know for sure why these children lost an excessive amount of weight. But our hypothesis is that they were born with more extra fluid than normal and so some of the weight they lost was fluid,” Chantry said. The authors said some mothers receive intravenous fluids during delivery to protect them against a drop in blood pressure in response to epidural anesthesia. The babies may have lost more weight by voiding some of the extra fluid their mothers received, the authors said.
Human milk is the healthiest milk for human infants, and lowers the likelihood of both infections, such as diarrhea and pneumonia, as well as chronic diseases such as childhood cancer.
Breastfeeding also protects the mother against diseases such as cancer, diabetes and heart disease. Improving rates of breastfeeding exclusivity and duration are among the national Healthy People 2010 goals.
The breastfeeding study was conducted in 316 diverse, first-time diverse, suburban and urban mothers and their babies at UC Davis Medical Center in Sacramento, Calif., between January 2006 and December 2007. The mothers were enrolled between their 32nd and 40th weeks of gestation. All the women gave birth to one child; no multiple births were included in the study.
The study participants were visited within 24 hours by lactation specialists to study their breastfeeding behaviors and problems, formula and pacifier use and the onset of milk production, or lactogenesis. The babies were weighed at days three and seven days either in the home, the hospital or at a follow up clinic visit. Some 134, or 42 percent, of the mothers breastfed their infants exclusively during the first three days after delivery; 95, or 30 percent, of infants received minimal formula supplementation.
The authors also note that previous studies have found an association between pain management for women, such as epidurals, and excess weight loss among their infants. Medicated deliveries were nearly “universal” among the study’s participants, precluding evaluation of this association.
“Physiologically babies don’t need many calories in the first few days of life and all full-term healthy babies are born with extra fluid,” Chantry said. “Weight loss is a normal adaptation in the first few days of life. Losing up to 10 percent of their body weight is considered normal — but above 10 percent is a concern.”
Avoiding excess weight loss is a good thing, Chantry said. We do know of maternity practices that increase breastfeeding success, such as early initiation of breastfeeding. It will be important to determine if less aggressive fluid administration during labor, when appropriate, lowers the incidence of the number of infants experiencing excess weight loss.
“We need to better understand the significance of weight loss when mothers have received a lot of intra-partum fluids. It may be that more weight loss in this setting is acceptable. We know that in-hospital formula supplementation greatly increases the risk of early breastfeeding cessation even when the mothers are committed to breastfeeding. We need to better learn exactly who needs the supplementation and how we can mitigate the negative effects of supplementation for those who do need them,” she said.
“We also need to support all women and babies to be able to achieve their breastfeeding goals, whether or not supplements are needed.”
The UC Davis School of Medicine is among the nation’s leading medical schools, recognized for its research and primary-care programs. The school offers fully accredited master’s degree programs in public health and in informatics, and its combined M.D.-Ph.D. program is training the next generation of physician-scientists to conduct high-impact research and translate discoveries into better clinical care. Along with being a recognized leader in medical research, the school is committed to serving underserved communities and advancing rural health. For more information, visit UC Davis School of Medicine at medschool.ucdavis.edu.