By Anne Harding
Infants who are heavier in the first six months of life are more likely to develop recurrent wheezing by age three, putting them at increased risk of being diagnosed with asthma later on, researchers from the Harvard Medical School and the Harvard School of Public Health in Boston report.
"We are clearly seeing that rapid growth early on is associated with adverse outcomes later on," Dr. Elsie M. Taveras, the study's lead author, told Reuters Health. However, she added, the jury is still out on what parents can do to help babies gain the right amount of weight as they grow.
"There's an open call for researchers to really study what we should be telling parents about early infancy growth," said Taveras, who is also affiliated with Harvard Pilgrim Health Care.
Several studies have linked obesity to asthma, but most have looked at only a single point in time, so they couldn't show whether obesity leads to asthma or vice versa, she added. To better understand the relationship, Taveras and her team followed 932 children from birth to three years of age.
The greater an infant's weight for his length at six months exceeded the average, the more likely the child's parents were to report recurrent wheezing, the researchers found.
Asthma risk also rose with weight for length, but the relationship wasn't as strong, probably because children are rarely diagnosed with asthma before age five, according to Taveras. "What most clinicians will do before that age is diagnose wheezing," she explained.
The researchers provide an example: if two six-month-old boys are both of average length (67 centimetres), if one child weighed 8,4 kilograms, he would be 46 percent more likely to have recurrent wheezing by age three than the other child, if he was an average weight (7,7kg).
There are a number of ways that excess fat could contribute to asthma risk, Taveras noted, for example by affecting inflammation or even making it more difficult for a child to fully expand his or her lungs. "There are a lot of remaining questions in that area," she said.