Future moms who take the popular pain reliever acetaminophen, commonly known as Tylenol or Triaminic, during pregnancy could be increasing their child’s chance of wheezing, a common symptom of asthma, a new review of studies suggests.

For children of women who used acetaminophen (also known as paracetamol) during pregnancy, the risk of wheezing between ages 2½ and 7 was 21 percent higher than for children of non-users, based on the review of six studies.

However, there was no wheezing risk associated with aspirin or ibuprofen use during pregnancy, according to the review.

Acetaminophen, an over-the-counter pain reliever and fever reducer, is commonly used to relieve pain from headaches and other minor aches. It’s not completely known why the drug is associated with asthma risk, but it probably has to do with an increase in oxidative stress in the lungs, said Dr. Todd Rambasek, an allergist at ENT & Allergy Health Services in Ohio, who was not involved with the study.

Oxidative stress is caused by free radicals, charged particles — produced from reactions in our body and from air pollution — that can cause cell death or damage. Oxidative stress in the lungs, caused by inhaled air pollution, is a known contributor to asthma , Rambasek said.

Human bodies have natural antioxidant defenses to stabilize these free radicals. But when women who possess a particular gene ingest acetaminophen, the acetaminophen consumes and depletes the body’s antioxidants, he said.

“Since oxidative stress is a big part of asthma, that just overwhelms your antioxidant defenses and you get asthma ,” Rambasek told MyHealthNewsDaily. “It basically depletes their antioxidant system.”

Women can then pass on this oxidative stress to the babies developing in the womb, which could increase the wheezing risk, he said.

While pregnant women shouldn’t rule out all acetaminophen use to relieve pain during pregnancy, they should take the drug only sparingly and when absolutely necessary, Rambasek said.

The study was published this week in the journal Clinical & Experimental Allergy.

Pass it on: Pregnant women should take acetaminophen only when absolutely necessary, because the drug has been shown in studies to slightly raise the risk of wheezing during childhood.

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