What Might Breastfeeding Now Mean Later?

Breastfed children less likely to be overweight or obese in long term study

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Most mothers have the option of feeding their child formula or breastfeeding, or a mixture of both. Choosing breastfeeding might have benefits for children's weight down the line.

A recent study found that children in Japan who were breastfed were less likely to be obese than children who were formula fed.

Even children who were partially breastfed for a few months saw some reduced risk of being overweight.

The longer the children were exclusively breastfed, up to 6 or 7 months, the less likely they were to be overweight or obese.

"Try to breastfeed your baby for at least six months."

This study, led by Michiyo Yamakawa, MHSc, of the Department of Epidemiology at Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences in Japan, looked for any links between children being breastfed and being overweight or obese in childhood.

The researchers analyzed data on 43,367 children born at at least 37 weeks of pregnancy.

Using information about the infants' feeding practices, the researchers divided the children into five non-overlapping categories:

  • exclusively formula fed
  • partially breastfed for 1-2 months
  • partially breastfed for 3-5 months
  • partially breastfed for 6-7 months
  • exclusively breastfed until 6 to 7 months old

Then, the researchers compared the babies in these categories to where they fell in the categories of "underweight, normal weight, overweight and obesity" at ages 7 and 8.

The children's body mass index (BMI), based on their age and sex, was used to determine if they were a healthy weight. BMI is a ratio of a person's height to weight.

In doing their analysis, the researchers made adjustments to take into account the children's sex, TV watching time and computer game playing time because these also can affect weight.

The researchers also took into account the mothers' education levels, employment status and smoking (or not smoking). These factors can also be related to children's weight.

The researchers found that children who were exclusively breastfed until they were 6 to 7 months old were about 15 percent less likely to be overweight and were nearly half as likely to be obese at age 7, compared to children who were exclusively formula fed. Similar results were found for the children at age 8.

Children who were partially breastfed for anywhere from 1 to 7 months were about 10 to 14 percent less likely to be overweight and 30 to 44 percent less likely to be obese.

"Breastfeeding is associated with decreased risk of overweight and obesity among schoolchildren in Japan. Therefore, it would be better to encourage breastfeeding even in developed countries," the authors wrote.

This study was limited by the fact that more children were initially included in the analysis but were lost during the follow-up period.

There also may be factors that the authors did not adjust for that could be related to children's risk of being overweight, such as the mother's weight, genetics and other lifestyle behaviors besides TV and computer games.

This study was published August 13 in the journal JAMA Pediatrics. The authors declared no conflicts of interest.

The research was funded by the Ministry of Health, Labour and Welfare Health, the Sumitomo Foundation and the Labour Sciences Research Grants on Health Research on Children, Youth and Families.

Review Date: 
August 13, 2013
Last Updated:
August 15, 2013