Younger Siblings and Kids' Obesity Risk
But children who didn't have a younger sibling by first grade much more likely to be obese
By Kathleen Doheny
FRIDAY, March 11, 2016 (HealthDay News) -- Children who have younger siblings before they reach first grade may be less likely to become obese, new research suggests.
If they are between the ages of 2 and 4 when a second child arrives, they "are significantly less likely to end up being obese," said study author Dr. Julie Lumeng, an associate professor of pediatrics at the University of Michigan, in Ann Arbor.
Conversely, those children who did not have a younger sibling born by the time they reached first grade were nearly three times more likely to be obese.
The study was published online March 11 and will appear in the April print issue of the journal Pediatrics.
About one in six children and teens in the United States is obese, putting them at risk for a host of other health problems, including type 2 diabetes, according to the U.S. Centers for Disease Control and Prevention.
Lumeng couldn't explain the association she found in the study. She pointed out that she found a link, but not a cause-and-effect relationship. "In the study we did, we did not have data that would help us understand the mechanism," she said.
The researchers analyzed data from nearly 700 children across the United States, tracking their weight status and whether they had a new sibling born before first grade.
Those who had a younger sibling born when they were between the ages of 3 and 4 had the least amount of obesity. Just under 5 percent of those children were obese by first grade. Of those who had a sibling born when they were 2 and 3 years of age, 8 percent were obese by first grade, the investigators found.
But nearly 13 percent of the children who did not have a younger sibling born by the time they reached first grade were obese, the findings showed.
When people hear the results, Lumeng said, they often ask if she is recommending women have more babies to save their children from obesity. Not at all, she said.