Hospitals May Overfeed Newly Born Babies With Formula

WINNIPEG, Manitoba -- Physiologically appropriate infant weight loss is less for babies fed formula in the hospital than for those who are breastfed, suggesting that hospitals feed too much, researchers said.

WINNIPEG, Manitoba, Aug. 22 -- Physiologically appropriate infant weight loss is less for babies fed formula in the hospital than for those who are breastfed, suggesting that hospitals feed too much, researchers here said.

Formula feeding in the first few days of life may lead to later overweight and obesity by way of metabolic imprinting, Patricia J. Martens, Ph.D., and Linda Romphf, of the University of Manitoba, reported online in the Journal of Human Lactation.

An earlier study had found that the first week of life was critical for humans, with each 100-g increase in absolute weight gain associated with a 28% increase in the odds of becoming an overweight adult.

After controlling for variables in the current study, exclusive formula feeding had the largest impact, with 3.1% less weight loss than exclusive breastfeeding, said the researchers, both international board certified lactation consultants.

The degree of weight loss is critical in the decision to supplement breast-fed infants, they wrote. However, given the overhydration of newborns, the early loss of meconium, and the small fluid intake in the first few days, weight loss is expected in the first few days.

Various pediatric textbooks and prospective studies indicate normal weight loss to be 5% to 7%, peaking on day three after birth, the researchers wrote. Weight loss for the breast-fed infants was within the normal range, whereas loss for the formula-fed newborns was lower.

The investigators determined weight loss and influencing factors for full-term newborns through 812 chart audits at six hospitals in the province of Manitoba.

With multiple regression analysis, they calculated the effects of parity, gestational age, birth weight, sex, length of hospital stay, type of delivery (cesarean versus vaginal), epidural use, and type of infant feeding (exclusively breastfed, partially breastfed, exclusively formula-fed) on percentage weight loss while still in the hospital.

Weight loss in the hospital was 5.09% 2.89% (95% CI, 4.89-5.29), varying by feeding category: exclusively breastfed 5.49% 2.60% (CI, 5.23-5.74) and partially breastfed 5.52% 3.02% (CI, 5.16-5.88). For formula-fed, weight loss was only 2.43% 2.12% (CI, 2.02-2.85).

Other factors significantly increasing percentage weight loss included higher birth weight, female sex, epidural use, and longer hospital stay.

Lower percentage weight loss was associated with greater gestational age and exclusive formula feeding. Parity and type of delivery were not significant.

Controlling for demographic and delivery-related variables, exclusive formula feeding had the largest impact, with 3.1% less weight loss than exclusive breastfeeding, the investigators said.

Discussing the significance of the findings, Dr. Martens said, postnatal nutritional exposures may program long-term biological responses.

Animal studies have found that overfeeding and rapid neonatal weight gain in the first few days of life lead to long-term obesity, possibly attributable to mechanisms related to gene expression, brain structure, and enzymatic function.

The type of feeding, the investigators said, may influence early intake volumes quite dramatically. Breastfed infants normally control the feeding patterns and intakes, which in turn affects the mother's breast milk production.

In contrast, the bottle-fed infant has less control over the energy and nutrient concentration of the formula offered. Formula-fed infants have much higher intakes compared with breast-fed infants during the first three days.

Discussing study limitations, the researchers said that the collected data were for clinical, not research, purposes, and may therefore have underestimated variables, such as the number of feeding episodes.

The weight loss modeled in this project, they said, may also represent an underestimation because once-a-day measures may not have captured the nadir.

Also some of the breast-fed infants received small amounts of supplementation, so that the finding that these infants experienced similar weight loss to exclusively breast-fed infants should be interpreted with caution.

The striking finding of this study is that formula-fed infants in the early days had a very different weight loss patterns, they wrote. These were around 3% less weight loss, or just over 100 g less weight loss, even during the hospital post-birth window.

The early feeding experiences of the newborn may be critical in metabolic imprinting, the researchers said, so that formula feeding could be biologically significant as a risk factor for later overweight or obesity.

Given these factors, they said, the type of feeding is critical in giving post-birth care, and the substantial difference in weight loss for these infants leads to the conjecture that formula-fed infants may be at risk for overfeeding even before hospital discharge.

Further study into physiologically appropriate intake volumes is critical, they said. In addition, breast-feeding supportive environments during the perinatal period are required to ensure necessary support and information to enable women to breastfeed, the lactation consultants concluded.