A large study has found that taking acetaminophen, the over-the-counter pain reliever also known as Tylenol and paracetamol, during pregnancy is associated with a slight increase in the risk for asthma for children.
The study was conducted in Norway and used health data from more than 95,000 women who were pregnant between 1999 and 2008 and who were enrolled in the Norwegian Mother and Child Cohort Study. The researchers then followed more than 53,000 of the children after the women gave birth. The mothers were asked to complete questionnaires on what medications they used for themselves and their children.
Researchers at the Norwegian Institute of Public Health controlled for several types of health and behavioral characteristics in the women and children in the study. They found that prenatal exposure to acetaminophen was associated with a 13% higher risk of asthma when the children were age 3. The more acetaminophen the mother had taken during her pregnancy, the higher the risk of asthma was for her child.
The study was designed so that it minimized the possibility that the increased risk of asthma was caused by an illness the mother had rather than by the Tylenol she had been taking. But even after controlling for several illnesses, the association between taking acetaminophen and asthma was still seen. It did not matter why the mother was taking the pain reliever, whether she took the medicine for pain, fever, or a respiratory tract infection, there was still a small increased risk of her child having asthma by age 3.
"Based on this modest increased risk, there is no need to be concerned if a child has been exposed," said the lead author, Maria C. Magnus, of the Norwegian Institute of Public Health, in an interview with The New York Times. "It might be possible to limit the amount of Tylenol used, but mothers should not be afraid to use it when necessary."
The study was published in the International Journal of Epidemiology.