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Kids' Asthma Tied to Mom's Acetaminophen Use

Heavy use late in pregnancy raises risk, study says

MONDAY, Oct. 28, 2002 (HealthDayNews) -- Women who frequently take painkillers like Tylenol late in pregnancy may increase the chances that their babies will suffer asthma after birth.

That's the conclusion of a new study by U.K. researchers who found that exposure to acetaminophen in the womb appears to double the risk of breathing trouble early in life.

However, only about 1 percent of women in the study took the painkiller every day or nearly that often late in their term, so only a few dozen babies in the study were affected. The researchers estimate that exposure to acetaminophen late in pregnancy may account for about 1 percent of early childhood asthma, a "very small" fraction of the total prevalence.

Babies whose mothers took aspirin frequently during pregnancy also seemed to suffer more wheezing, but only until they reached about 6 months of age.

A report on the findings appears in the November issue of the journal Thorax.

If true, the link between acetaminophen and childhood asthma would be yet another reason to use caution with the over-the-counter remedies. Last month, a panel of experts for the U.S. Food and Drug Administration called for clearer warning labels on packaging of drugs like Tylenol over concerns that people were unwittingly taking doses that could damage their liver.

Overdoses of acetaminophen, both intentional and accidental, are among the most common causes of adverse drug reactions in the world. The FDA has found that acetaminophen overdoses lead to more than 56,000 emergency room visits a year in the United States alone. Of those, about a quarter are unintentional, and 100 are deadly.

In the new study, a team led by Dr. Seif Shaheen of King's College in London looked at asthma and wheezing rates in 9,400 children when they were 30 to 42 months, or about 2.5 to 3.5 years old.

Only 1 percent of mothers took acetaminophen regularly or daily during the later part of their pregnancy, defined as 20 to 32 weeks of gestation. Yet their offspring had about twice the risk of wheezing or asthma as those whose mothers took less or none of the drug, and it was slightly higher for those who developed these problems before they reached 6 months of age.

The risk didn't hold for children whose mothers took the painkiller early in pregnancy but then stopped. Aspirin intake seemed to affect a baby's risk of wheezing during the first months of life, but the association was weak. Neither acetaminophen nor aspirin was associated with an increased risk of eczema, an allergic skin condition.

In earlier work, Shaheen's group found that people who take more acetaminophen are more prone to asthma and allergies, but iot hasn 't been proved whether the connection is causal. The researchers argue that the painkiller may damage lung cells through a process of oxidative stress. "Our latest results suggest that heavy fetal exposure to [acetaminophen] in late gestation may influence the inception of persistent wheezing in early childhood, thus lending support to the hypothesis that childhood asthma begins in utero," they wrote.

Dr. Lynn Taussig, president and chief executive officer of National Jewish Medical and Research Center, a leading asthma hospital in Denver, said he wasn't aware of a biological link between acetaminophen and airway problems. Even so, he added, at least some of the risk of childhood asthma can be explained by exposures in the womb to irritants the mother takes in.

However, Taussig said, the bulk of the allergy risk to infants comes from factors like exposure to tobacco smoke at home, certain infections, the size of their airways, and not being breast-fed.

An estimated 3.8 million children under age 18 in this country have asthma, according to the American Lung Association. The prevalence of asthma in children appears to have stabilized in recent years after having climbed sharply between 1980 and 1996.

What To Do

To find out more about asthma in children, try the Childhood Asthma Foundation or the American Lung Association.

SOURCES: Lynn Taussig, M.D., president and CEO, National Jewish Medical and Research Center, Denver; November 2002 Thorax
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