Pain drugs in pregnancy tied to ADHD

Short-term use does not appear to increase the risk for ADHD.


Women who use a lot of the common pain reliever paracetamol during pregnancy are more likely to be children with attention deficit hyperactivity disorder (ADHD) than those who do not make use of the drug, a Norwegian study suggests.

Researchers analyzed data on nearly 113,000 children and their parents, including 2,246 children who were diagnosed with ADHD. Almost half of the mothers took paracetamol (also known as paracetamol) at some point during the pregnancy, the researchers report in Pediatrics.

The use of the drug in only one trimester was associated with a 7 percent higher chance of having a child with ADHD, while the increased risk was 22 percent for women who paracetamol in two quarters, and 27 percent in use in all three trimesters, the study found.


Short-term use does not appear to increase the risk for ADHD. In fact, when the women took acetaminophen for less than 8 days, they were 10 percent less likely to have children with ADHD than mothers who do not make use of the medicine during the pregnancy, the study found.

Women used in medicine for fevers and infections for 22 to 28 days, however, were more than six times more likely to have children with ADHD than mothers who avoided the drug during pregnancy.

“Surprisingly, adjusted for all medical conditions associated with paracetamol use during pregnancy (e.g., infections and pain), and familial genetic risk factors for ADHD, children exposed to the long-term use of paracetamol during pregnancy more than two times more likely to have ADHD are diagnosed by a specialist in a clinic,” said lead study author Eivind Ystrom of the Norwegian Institute of public Health and the University of Oslo.

“This is important, because more than 50 percent of the women in the western countries make use of acetaminophen during pregnancy, a large number of children are also exposed to the long-term use,” Ystrom said by e-mail.

Overall, researchers estimate that about 4 percent of the children in the study would be a ADHD-diagnosis at the age of 13.

The study was not a controlled experiment designed to prove that the question of whether and how prenatal paracetamol use can lead directly to ADHD.


A limitation of the study is that long-term use of paracetamol during pregnancy may indicate a serious illness or injury, and researchers lacked data about the severity of the circumstances that have led women to use the drug.

Another disadvantage is that the researchers used survey data to determine when and how long the pregnancy women used paracetamol as well as the reasons that they took the drug. A lot of people in the study also does not report the reason for the use of paracetamol.

It is possible that the connections between paracetamol and ADHD in the study were purely due to chance, according to Dr. Antonio Saad, a researcher at the University of Texas Medical Branch in Galveston which is not involved in the study.

“You should also keep in mind that the use of acetaminophen can have negative consequences,” Saad said by e-mail. “Other pain and fever medications, such as ibuprofen, should not be used during pregnancy, which leaves drugs as the only alternatives for pain and no alternatives for the fever.”

Doctors usually advise pregnant women to take acetaminophen in the smallest dose possible for the shortest possible period of time when they have a fever.

“I don’t think that a very moderate dose of paracetamol in just a few days would have no real influence on the development of the brain,” Jordi Julvez, a researcher at the Barcelona Institute for Global Health, who was not involved in the study, said by e-mail.

The increased risk of ADHD linked to more use of acetaminophen can also result from the severity of the medical problems of the women, not the use of the drug, said Dr. Chittaranjan Andrade of the National Institute for Mental Health and Neuroscience in Bangalore, India.

A high fever or an infection, for example, may be the reason that babies developed ADHD, no paracetamol their mothers took, Andrade, who was not involved in the study per e-mail.

“The results of this study do not contribute significantly enough to discourage the use of (paracetamol) if indicated during each trimester during the pregnancy,” Andrade said.

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