Breastfeeding past two months helps babies avoid obesity

Infants at risk for childhood and adult obesity have a better chance of not becoming overweight if breastfeeding continues beyond two months, nutritional scientists at Cornell have discovered.

''Children at the highest risk for rising weight gain patterns in infancy appear to benefit the most from longer breastfeeding duration,'' Stacy J. Carling and research colleagues report in the study, ''Breastfeeding Duration and Weight Gain Trajectory in Infancy,'' published in the December 2014 issue of the journal Pediatrics.

''Infants who breastfed for two months or less were 2.5 times more likely to add weight rapidly, compared to similarly high risk children who breastfed longer,'' said Carling, a doctoral student in the field of nutritional sciences.

Excessive weight gain in infancy has been linked with obesity later in life and there are several well-known risk factors for that, Carling said: ''Our study is the first to show that stopping breastfeeding too soon tips the scale for at-risk children.''

The two-year study tracked 595 children in a health care system in central New York, asking mothers to fill out questionnaires and give access to the children's medical records.

Excessive (or normal) weight gain by the maturing infants was followed with their weight-for-length/height ''z scores,'' a standard measure used by the World Health Organization to detect malnutrition in children not gaining enough weight as their bodies lengthen.

On the mothers' part, risk factors for subsequent childhood obesity included maternal BMI (body mass index), education, gestational weight gain, food insecurity and smoking during pregnancy, postpartum stress and lack of social support. In the final analysis for this particular cohort, maternal BMI, education and smoking during pregnancy were the only factors associated with an infant's weight-gain trajectory.

''Now we can add short-duration breastfeeding to the list,'' said Carling, speculating on the mechanisms behind inappropriate weight gain in the first two years of life: ''Breastfeeding may protect against elevated infant weight gain – with better appetite control and lower protein intake – compared to formula-fed babies.''

Other researchers in the breastfeeding study are Margaret M. Demment, Ph.D. '13; Chris L. Kjolhede, M.D., Mary Imogene Bassett Hospital and Research Institute, Cooperstown, New York; and Christine M. Olson, professor of nutritional sciences in the College of Human Ecology.

The authors expect their findings will ''aid in the identification of infants at high risk for obesity … targeting mothers of high-risk infants for breastfeeding promotion and support may prove protective against overweight and obesity during a critical window of development when such efforts are most effective.''

The research was supported, in part, by funds from National Institutes of Health and the National Institute of Diabetes and Digestive and Kidney Diseases.

Baby knows best
Report author Stacy Carling has some ideas why breastfeeding keeps at-risk babies at a healthy weight:

''Breastfeeding, especially on demand (versus on a schedule), allows an infant to feed when he/she is hungry, thereby fostering an early development of appetite control,'' Carling says. ''When a baby breastfeeds, she can control how much milk she gets and how often, naturally responding to internal signals of hunger and satiation.

''Interestingly, the breast milk a baby receives in the beginning of a feeding (foremilk) and at the end of a feeding (hindmilk) varies in nutrient composition and triggers a physiological process of satiation,'' Carling observes. ''When a baby receives a bottle, nutrient composition doesn't vary over time of the feeding. And seeing milk remaining in the bottle may lead caretakers to encourage the baby to empty a bottle even when the infant is no longer hungry.

''Breastfeeding an infant may allow proper development of hunger and satiety signals,'' Carling concludes, ''and help prevent some of the behaviors that lead to overweight and obesity.''