Mom's Smoking Tied to Dangerous Gut Illness in Preemies

THURSDAY, June 14 (HealthDay News) -- Mothers who smoke while pregnant may raise the risk that, if born prematurely, their babies will develop a serious and perhaps life-threatening bowel disease known as "necrotizing enterocolitis," a small new study has found.

Although its underlying cause is poorly understood, necrotizing enterocolitis poses the most common gastrointestinal emergency in premature babies, the study authors noted. The disease destroys tissue in the lining of the intestinal walls of newborns.

To date, no specific cause for necrotizing enterocolitis has been determined, although many post-birth factors -- including bacterial infection, mechanical ventilation and formula-feeding -- have been implicated in its onset, according to background information in the study. But the current study involving 73 infants suggests maternal smoking could be a key prenatal harbinger of the condition.

"We tried a different line of thinking for an intestinal disease among premature babies that we don't have a defined association for, by looking at several factors during pregnancy that could play a role," said study lead author Dr. Cynthia Downard, assistant professor of pediatric surgery at the University of Louisville in Kentucky.

"And, in fact, the only [factor] that was statistically significant was maternal smoking, which I think gives yet more credence to obstetricians and pediatricians to advise that women stop smoking during pregnancy," she said.

The study is published in the July issue of the journal Pediatrics.

Downard noted that roughly 7 percent to 10 percent of all American infants develop necrotizing enterocolitis, making it one of the most prominent causes of death among premature babies.

To explore potential prenatal causes, the team analyzed the medical records of 73 premature babies who were hospitalized for necrotizing enterocolitis in the intensive care unit of a single hospital at some point between 2004 and 2009.

The researchers looked at the mothers' prenatal and postnatal status, including maternal smoking history, blood pressure, body mass index, age and diabetes incidence, as well as data on the labor itself and post-labor feeding routines.

The result: Maternal cigarette smoking was the sole factor that was linked to an elevated risk for necrotizing enterocolitis.

The authors theorized that the toxins and nicotine found in cigarettes have a harmful effect on the uterine environment to which the fetus is exposed, perhaps affecting the gestating child's vascular development and, in turn, rendering the child more vulnerable.

Smoking during pregnancy also puts babies at higher risk for being underweight and having birth defects such as cleft lip and cleft palate, according to the March of Dimes.

The research team said this is the first time maternal smoking has been "definitively" associated with necrotizing enterocolitis among preemies.

"Now the question to ask is whether or not nicotine patches [to help pregnant women quit smoking] would also do the same harm," Downard said. "We don't have that information in the maternal records, so we don't know. But I do think it would be associated to a certain extent, although hopefully not to the same extent long term."

Commenting on the study findings, Dr. Mary Rosser, an assistant professor in the department of obstetrics, gynecology and women's health at Montefiore Medical Center and Albert Einstein College of Medicine in New York City, said: "We always talk about necrotizing enterocolitis associated with preterm delivery and prematurity, because it is, as [the study authors] point out, the most common gastrointestinal emergency among premature infants."

And, she added, "on the other hand, cigarette smoking is also correlated with preterm labor, preterm delivery and low birth weight babies. So this work is interesting because it puts both of those facts together."

More research is needed, said Rosser, especially in light of how much nicotine is "absorbed by the baby, which will definitely affect the baby's vascular development."

While the study uncovered an association between smoking during pregnancy and necrotizing enterocolitis in preemies, it did not prove a cause-and-effect relationship.

More information

For more on necrotizing enterocolitis, visit the U.S. National Library of Medicine.

SOURCES: Cynthia Downard, M.D., assistant professor, division of pediatric surgery, University of Louisville, Louisville, Ky.; Mary L. Rosser, M.D., Ph.D., assistant professor, department of obstetrics, gynecology and women's health, Montefiore Medical Center, Albert Einstein College of Medicine, New York City; July 2012, Pediatrics

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