Women who use a lot of the common pain reliever acetaminophen during pregnancy may be more likely to have children with attention deficit hyperactivity disorder (ADHD) than those who don’t use the drug, a Norwegian study suggests.
Researchers analysed data on almost 113 000 children and their parents, including 2 246 kids who were diagnosed with ADHD.
Almost half of the mothers took acetaminophen (also known as paracetamol) at some point during pregnancy, researchers report in Pediatrics.
Using the drug during just one trimester was associated with 7% higher odds of having a child with ADHD, while the increased risk was 22% for women who used acetaminophen in two trimesters and 27% with use in all three trimesters, the study found.
Short-term use didn’t appear to increase the risk for ADHD. In fact, when women took acetaminophen for less than 8 days, they were 10% less likely to have kids with ADHD than mothers who didn’t use the drug at all during pregnancy, the study found.
Women used the medicine for fever and infections for 22 to 28 days, however, were more than six times more likely to have kids with ADHD than mothers who avoided the drug during pregnancy.
Overall, researchers estimated that about 4% of the children in the study would have an ADHD diagnosis by the age of 13.
The study wasn’t a controlled experiment designed to prove whether or how prenatal acetaminophen use might directly cause ADHD.
One limitation of the study is that long-term use of acetaminophen during pregnancy might indicate a more serious illness or injury, and researchers lacked data on the severity of conditions that led women to use the drug.
Another drawback is that researchers relied on survey data to identify when and how long in pregnancy women used acetaminophen as well as the reasons they took the drug.
It’s possible that the connections between acetaminophen and ADHD in the study were merely due to chance, said
Dr Antonio Saad, a researcher at the University of Texas Medical Branch in Galveston
who wasn’t involved in the study.
“One also has to keep in mind that not using acetaminophen can have negative consequences,” Saad said by email.
“Other pain and fever medications, such as ibuprofen, should not be used in pregnancy, which leaves narcotics as the only alternatives for pain and no alternatives for fever.”
Doctors generally advise pregnant women to take acetaminophen in the smallest dose possible for the shortest possible period of time when they have fevers.
“I don’t think that a very moderate dose of acetaminophen during only a few days would have any real effect on the developing brain,” Jordi Julvez said by email.
Julvez is a researcher at the Barcelona Institute for Global Health who wasn’t involved in the study.
The increased risk of ADHD linked to longer use of acetaminophen might also be due to the severity of medical problems women had, not their use of the drug, Dr Chittaranjan Andrade of the National Institute of Mental Health and Neurosciences in Bangalore, India, said.
A serious fever or infection, for example, might be the reason babies developed ADHD.
Not acetaminophen their mothers took, Andrade, who wasn’t involved in the study said by email.