A new study has found that breastfeeding higher birth weight infants for at least 6 months significantly reduces their chances of becoming overweight or obese in childhood.

New mothers who are breastfeeding high-birthweight infants, may probably be protecting them from being overweight or obese in childhood, a new study suggests. "High birthweight is associated with overweight or obesity during early childhood. Among high-birthweight infants, exclusive breastfeeding is a significant protective factor against overweight and obesity," said lead study author Hae Soon Kim, from the Ewha Womans University College of Medicine in Seoul.

For the study, presented at the ENDO 2018: The Endocrine Society's 100^th Annual Meeting and Expo, researchers investigated the weight-growth trajectory and the protective effect of breastfeeding for obesity in children. They analysed data between January 1, 2008 and December 31, 2016. The researchers followed 38,039 participants who were completely eligible for all health checkups from birth through six years of age. At each check-up period, the researchers examined the association between birthweight status and growth development.

Infants were assigned to one of three groups by birthweight: the low-birthweight group, less than or equal to 2,500 grams; the normal-birthweight group, over 2,500 grams and under 4,000 grams; and the high-birthweight group, 4,000 grams or more. During the follow-up period, about 10 per cent of the low-birthweight infants and 15 per cent of the normal-birthweight developed obesity or overweight. By contrast, more than 25 per cent of the high-birthweight infants met the criteria for obesity or overweight.

The high-birthweight infants were highly likely to be overweight or have obesity compared with normal birthweight infants through six years of age, and the low-birthweight infants were highly likely to be underweight through six years of age, the researchers said. The risk of overweight or obesity decreased significantly if high-birthweight infants were exclusively breastfed for the first six months of life, they noted.