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Prenatal Acetaminophen: An Asthma Link?

Pregnant Women Who Take Acetaminophen Could Raise Asthma Risk in Their Kids

Study Details

The analysis, part of an ongoing study looking at the effect of pollutants ranging from secondhand smoke to pesticides on children's health, involved 712 nonsmoking mothers of African-American and Dominican ethnicity. All lived in low-income neighborhoods in New York City.

Once a year, the women were asked detailed questions about whether they or their children had symptoms of asthma and allergy. They were asked about their and their children's use of prescription and over-the-counter medications. With regards to the current analysis, Perzanowski says, "the specific question that women were asked was, 'Did you take Tylenol in pregnancy, and if so, for how many days?'" Additionally, their blood was tested for chemicals that have been implicated in the allergic cascade.

Overall, 34% of the moms took acetaminophen in pregnancy.

Wheezing rates among 5-years-olds were:

  • About 22% if their moms didn't take acetaminophen in pregnancy.
  • About 30% if they took it for one day.
  • More than 35% if they took it for two to four days
  • More than 50% if they took acetaminophen for five or more days

Compared with 5-year-olds of moms who didn't take acetaminophen in pregnancy, those whose moms took it for five or more days were 2.2 times more likely to have wheezing at age 5. If a mom took acetaminophen for two to four days, the risk went up 78%. Taking it for one day did not significantly raise the risk.

Perzanowski says that the women were also asked how much Tylenol they took, but the data are not yet fully analyzed. "But it looks like they support the current findings -- that is, the more Tylenol they took, the greater the risk their child had wheezing at age 5," he says.

The analysis took into account other risk factors for asthma including ethnicity, whether the mom had asthma, and whether she smoked during pregnancy.

So what could be happening? While no one knows for sure, Perzanowski says that acetaminophen use may deplete the lung of an antioxidant called glutathione. Researchers think glutathione, which is found in the lining of airways, may play an important role in preventing damage to the lungs.


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