WEDNESDAY, Sept. 27 (HealthDay News) -- Low-birth-weight babies appear to be at significantly higher risk of developing irritable bowel syndrome (IBS) in later life, Norwegian researchers report.

IBS is a chronic bowel ailment characterized by cramping, bloating, gas, diarrhea and constipation.

Now, the new study finds that "restricted fetal growth significantly affected susceptibility to IBS later in life," according to lead researcher Dr. May-Bente Bengtson, from the department of medicine at the University of Oslo.

She added that "the rate of IBS was significantly higher in women compared with men, and [the] genetic contribution appeared to be important for IBS among females," she said.

The report was published in the Sept. 27 online edition of the journal Gut.

In the study, Bengtson's team tracked the health of 3,334 twin pairs, 1,250 of whom were identical twins. The twins filled in a questionnaire about their health, including whether they had ever had IBS. The data were then matched with their weight at birth.

Among all the twins, the rate of IBS was 5.4 percent, about one in 20. However, the IBS rate among women was 7 percent, compared with just 3 percent among men, the researchers found.

Furthermore, the risk of developing IBS was 2.5 times greater among those whose birth weights were below 1,500 grams (3.3 pounds) compared with those weighing more than 2,500 grams (5.5 pounds) at birth. The risk was generally higher for the lower-weight baby of the twin pair, the researchers found.

Bengtson's team also found that babies who weighed less than 1,500 grams tended to develop IBS symptoms some 7.7 years earlier compared with babies weighing more than 1,500 grams.

"Like other twin studies, we have shown that restricted birth weight, when below 2500 grams, increases the risk of morbidity, and the risk increases with decreasing birth weight," Bengtson said. "Convincing evidence exists to suggest that restricted development of specific fetal organs could predispose [individuals] to other chronic diseases like cardiovascular heart disease, non-insulin diabetes and hypertension."

The average age of IBS onset was similar for both men and women, with the first signs of the illness appearing at about the age of 18 in men, and a year earlier in women.

In addition, the likelihood of IBS was stronger among the identical twins, suggesting that genetic factors play a key role in the illness.

Growth of the bowel is a dynamic process that is ongoing at birth, Bengtson noted. She speculates that a "lack of [fetal] nutrition might disturb the development of the gut and the nervous system, and thereby cause symptoms of IBS, like abdominal pain, bloating and disturbed defecation," she said.

One expert said the connection between IBS and low birth weight is a new finding, but needs explaining.

"There is one question regarding their interpretation of results -- is this a genetic effect or is this a result of parental concern over a twin who weighs significantly less than the other twin?" said Dr. Charles Gerson, a clinical professor of medicine at Mount Sinai School of Medicine, New York City. For example, parents might feed a lower-weight twin differently than they do the larger twin, he said.

The important role of genes in IBS in twins is already known, Gerson said, but "interpretation of data in IBS is always confounded by psychosocial variables," he said.

More information

Find out more about IBS at the U.S. National Institute of Diabetes, Digestive and Kidney Diseases.

SOURCES: May-Bente Bengtson, M.D., department of medicine, University of Oslo, Norway; Charles Gerson, M.D., clinical professor, medicine, Mount Sinai School of Medicine, New York City; Sept. 27, 2006, online edition, Gut

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