Poor Health Linked to Very Preemie Birth Stabilizes by Adolescence
TUESDAY, July 26 -- Children who are born at extremely low birth weights (below 2.2 pounds) are susceptible to a number of chronic health conditions, such as asthma. But, new research suggests that between 8 and 14 years of age, any lingering chronic illness in extremely low birth weight babies tends to stay about the same -- not getting better, but also not getting worse.
Ironically, the one exception was obesity. The rate of obesity was 12 percent when the children were 8 years old, but by 14, the rate of obesity was 19 percent in the extremely low birth weight group. Rates of obesity in children who were born at normal weights were 16 percent at age 8 and 20 percent at age 14, according to the study.
"As these children get older, most conditions are stable, but they did catch up in obesity," said the study's lead author, Dr. Maureen Hack, a professor of pediatrics and co-director of high risk follow-up at Case Western Reserve University in Cleveland, Ohio.
That means that parents of children who were born at an extremely low birth weight should be aware that their children are at risk of becoming obese later in life. She said these findings suggest that in addition to a healthy diet, parents should encourage exercise in their children, to help keep weight in the normal range.
The findings are published in the July 27 issue of the Journal of the American Medical Association.
Before the 1990s, babies who were born at extremely low birth weights often didn't survive. But, changes in postnatal medical care in the 1990s improved survival for these tiny infants, according to background information in the study. What wasn't clear, however, was how these smallest of babies would do in the long term.
To get a better idea of how these children fared as they grew up, the researchers began following a group of extremely low birth weight babies who were born between 1992 through 1995 at Rainbow Babies and Children's Hospital in Cleveland.
The current study includes information from 181 of those children when they were between the ages of 8 and 14 years old. The researchers compared this group of children to a group that was the same age, but born at normal weights.
Parents filled out questionnaires regarding their child's health, and brief physical assessments were conducted.
The researchers found that the overall rates of chronic conditions remained stable from 8 to 14 years old for the extremely low birth weight children. Rates of asthma stayed the same -- at 23 percent from 8 to 14 years old for extremely low birth weight children. That trend held true even as the number of kids with asthma increased dramatically for teens born at a normal birth weight, rising from 8 percent to 17 percent.
The rates of functional limitations in the low birth weight group actually decreased during the age 8 to 14 time period, from 56 percent to 46 percent, the study found.
However, obesity rates rose. When the extremely low birth weight group was 8 years old, just 12 percent of them were obese. By 14 years, 19 percent of these children were considered obese. That compares to a 20 percent rate of obesity at age 14 for the children born at normal weights, according to the study.
Hack said the researchers aren't sure why rates of obesity increased so significantly during this time period. There are some factors that may make children born at extremely low birth weights more susceptible to gaining weight, however. She said that periods of very rapid growth at young ages may make later weight gain more likely. And, she said, previous research has shown that children who are born prematurely often exercise less than their peers born at term.
"Very low birth weight infants seem to be more at risk for obesity," said Dr. Dilek Bishku, pediatrician and vice president of medical affairs at La Rabida Children's Hospital in Chicago. But, she added, when they're younger, they're also at risk for malnutrition.
"We should approach the idea of catch-up weight in extremely low birth weight children with an open mind, because there's still a lot we don't know. And, this study doesn't definitively tell us what to do," she said.
Learn more about low birth weight babies from the March of Dimes.
Posted: July 2011
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