TUESDAY, Feb. 3, 2004 (HealthDayNews) -- The longer women breast-feed their babies, the less likely the children are to become overweight, a new study says.
That's true, at least, for non-Hispanic white children. Breast-feeding did not protect against excessive weight gain in some black and Hispanic children, the U.S. researchers add.
The study, appearing in the February issue of Pediatrics, provides the most conclusive evidence to date that prolonged breast-feeding can help reduce the risk of obesity.
"There are continued benefits to continuing breast-feeding," says study author Laurence Grummer-Strawn, chief of the U.S. Centers for Disease Control and Prevention's Maternal and Child Nutrition Branch.
The CDC researchers based their conclusions on an analysis of 177,304 children up to 5 years old, and a subset of 12,587 mother-child pairs, making it the largest breast-feeding study to date. Previous studies have yielded contradictory results.
By highlighting a key benefit of prolonged breast-feeding, the study also bolsters recommendations that mothers breast-feed their babies for at least a full year. The American Academy of Pediatrics, for one, encourages breast-feeding for at least 12 months to provide the fullest benefits for baby.
"If you breast-feed your babies, your children are more likely to have a reduction in illness, and one of those is obesity," says Dr. Lawrence Gartner, chairman of an American Academy of Pediatrics' panel on breast-feeding.
Obesity has become a worrisome problem in the United States. An estimated 15 percent of children and teens aged 6 to 19 are overweight, according to a 1999-2000 federal survey. The growing girth of America's youth poses serious health consequences, placing kids at higher risk of diabetes, hypertension, cardiovascular disease and certain types of cancer.
To examine the possible connection between prolonged breast-feeding and reduced risk of overweight, the CDC researchers looked at information from the Pediatric Nutrition Surveillance System. This survey captures data from children seen at public health clinics across the United States.
The team examined how long children nursed and their body mass index (BMI) -- a measure of weight in relation to height -- at 4 years of age. Children with a BMI that topped the 95th percentile for their age were considered overweight.
More than two thirds of children in the study -- 71.1 percent -- were never breast-fed, and only 6.1 percent were breast-fed for six months or more.
Kids who were never breast-fed or who were breast-fed for less than one month were most likely to be overweight at age 4, the study found. With increased breast-feeding duration, the rate of overweight kids declined.
For example, 13.6 percent of those who were never breast-fed and 13.7 of those who were breast-fed less than a month were overweight at age 4. By contrast, among those who were breast-fed for more than 12 months, 11 percent were overweight.
Breast-fed children were also less likely to be underweight, the study found.
Mothers-to-be might be asking themselves why the big fuss over a couple percentage-points difference between prevalence of overweight among bottle-fed kids and those who were breast-fed more than a year.
"It is a small difference," Grummer-Strawn admits, but it is significant. "What we're talking about is 'What are the things we can do to prevent overweight?'" he says. Breast-feeding is clearly one of those things.
How long-term breast-feeding protects against obesity isn't clear, although studies suggest several possible explanations. One is that a breast-fed child can self-regulate his or her caloric intake better than a bottle-fed child, whose parents may insist the baby finish off a pre-measured amount of formula.
Breast-feeding, of course, is only one factor influencing a child's risk of obesity. The study authors note that Hispanic children are nearly twice as likely to become overweight as non-Hispanic children "probably because of different dietary and physical activity patterns."
Parents' introduction of solid foods or exclusive reliance on breast-feeding may also differ along racial and ethic lines. For example, many Hispanic mothers combine breast-feeding with bottle feeding, and that may explain the weaker effect of breast-feeding in that group, Gartner says.
Still confused about whether to breast or bottle feed? For many moms, this study seems to provide another piece of evidence that the breast is best for baby.
"You can't beat Mother Nature," Gartner quips.