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Premature Birth Linked to Insulin Resistance

Study suggests metabolic processes may be programmed during pregnancy

WEDNESDAY, Nov. 17, 2004 (HealthDayNews) -- Can what happens in the womb affect your health years later?

Perhaps, says a new study that found premature infants -- whether small or the appropriate size for their gestational age when they were born -- used insulin about 60 percent less efficiently than their peers who were born at full-term.

The study by New Zealand researchers appears in the Nov. 18 issue of the New England Journal of Medicine.

"There's a notion that if you're deprived of food in the womb, you may be programmed for a lower nutritional intake," said Dr. Mark Sperling, a professor of pediatrics in the division of endocrinology at the University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh. Sperling authored an editorial about the study in the same issue of the journal.

This programming then becomes a problem if the baby goes from an environment of nutritional deprivation to abundance, as is the case in many areas of the world today, Sperling said.

"[This programming] may set the body up and predispose it to obesity, diabetes and metabolic syndrome," he added.

Insulin resistance -- the body's inability to use the hormone properly -- can be a precursor to type 2 diabetes, but not always. Sperling and Dr. Brenda Kohn, a pediatric endocrinologist at New York University Medical Center, both pointed out that it's important to realize that even though the premature children in the study showed signs of insulin resistance, it doesn't mean a later diagnosis of diabetes is a sure thing.

"The idea that the in-utero environment can have an impact on adult morbidity is very intriguing, but we can't say that insulin resistance from prematurity will result in type 2 diabetes later on," Kohn said.

"You can have transient insulin resistance that goes away," she explained.

More than 18 million Americans have diabetes, and as many as 95 percent of those cases are type 2 diabetes, according to the American Diabetes Association. Currently, about 200,000 children in the United States have diabetes.

The new study compared 50 children who had been born prematurely to a control group of 22 children who were born full-term. The children were between the ages of 4 and 10. Thirty-eight of the premature infants were born at the proper gestational weight, while 12 were small for their gestational age. None of the children in the control group was small for his or her gestational age.

Weight didn't seem to affect insulin resistance, according to the study. Insulin sensitivity was reduced by about 60 percent for the appropriate-weight premature infants, and about 65 percent for the small preemies, when compared to the control children.

The amount of insulin released into the blood was much higher in both premature groups than in children in the control group. In the control group, acute insulin release was 1,148 pmol/liter, while it was 2,002 pmol/liter for the average weight premature children and 2,253 pmol/liter for the small premature children.

"The subjects had a similar reduction in insulin sensitivity whether they had been born at 24 or 32 weeks' gestation, suggesting that there is a critical window during this time in which insulin sensitivity is permanently altered," wrote the authors, who added there is still debate over whether these changes are permanent.

Sperling said the finding is exciting because it gives doctors a potential way to head off insulin resistance, at least in premature infants, by providing optimal nutrition or other necessary interventions.

He said the study also draws attention to the need to make sure pregnant women have access to the health care and nutrition they need.

Kohn added that it's important to emphasize good child-rearing and healthy lifestyles as well. Whether or not a child was premature, if he or she is obese, they're at greater risk of developing type 2 diabetes.

More information

For more information about premature infants, including risk factors for premature birth, visit the National Library of Medicine.

SOURCES: Mark Sperling, M.D., professor, pediatrics, division of endocrinology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh; Brenda Kohn, M.D., pediatric endocrinologist, New York University Medical Center, and associate professor, pediatrics, New York University School of Medicine, New York City; Nov. 18, 2004, New England Journal of Medicine
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