Prolonged use of acetaminophen -- a pain-reliever that sometimes goes under the Tylenol trade name -- has been linked to increased risk of autistic spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), according to a new study by researchers at the Hebrew University of Jerusalem. The study sheds new light on the possible relationship between prolonged use of acetaminophen (paracetamol) during pregnancy and the risk of neurodevelopmental disorders in childhood.
Acetaminophen is one of the most common medications used for treatment of pain and fever reduction during pregnancy and is considered safe in humans. However, evidence of neuro-disruptive properties is accumulating: past studies have shown that long-term administration of low doses of acetaminophen may affect the development of the fetal nervous system, and that this effect is often seen years after exposure during childhood.
Dr. Ilan Matok and fellow researchers at the Institute for Drug Research in the School of Pharmacy at the Hebrew University's Faculty of Medicine have conducted a systematic review and meta-analysis to assess the possible association between prolonged exposure to acetaminophen during pregnancy. Appearing in the American Journal of Epidemiology, the study shows that prolonged exposure to acetaminophen during pregnancy is associated with a 30 percent increase in relative risk for ADHD (compared to those who did not take acetaminophen during pregnancy) and a 20 percent increase in relative risk for ASD.
This is the first meta-analysis and the most comprehensive study ever conducted on the possible association between prolonged use of acetaminophen during pregnancy and risk of autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD). The research data covered 132,738 mother and child pairs with a follow-up period of 3-11 years.
Given the significant limitations of existing studies, the researchers believe the results should be interpreted with caution, as they may cause unnecessary anxiety among pregnant women. It is important to understand that pain and fever during pregnancy can have a detrimental effect on the developing fetus and that acetaminophen is still considered a safe drug for use during pregnancy. Therefore, if a pregnant woman has fever and/or pain, acetaminophen can be taken for a short period, and if the fever or pain continue beyond that, she should consult her physician regarding further treatment
"Our study provides the first comprehensive overview of developmental outcomes following prolonged acetaminophen use during pregnancy," said Dr. Matok. "Our findings suggest an association between prolonged acetaminophen use and an increase in the risk of autism and ADHD. However, the observed increase in risk was small, and the existing studies have significant limitations. While unnecessary use of any medication should be avoided in pregnancy, we believe our findings should not alter current practice and women should not avoid use of short term acetaminophen when clinically needed."
Acetaminophen (paracetamol) is the active ingredient in many over-the-counter medications, and is frequently prescribed to pregnant women to reduce pain and fever. Currently, about Around 65 percent of pregnant women in the US take the drug when expecting, according to the Centers for Disease Control and Prevention.
According to another study, which was released in January, taking the painkiller during pregnancy may delay babies’ learning of speech. Pregnant women who use acetaminophen are more than six times during their early pregnancies are much more likely to have daughters with limited vocabularies, according to the study by Dr. Shanna Swan of Mount Sinai Hospital, New York City. It is not clear why boys appear to be unaffected. Dr. Swan concluded that women should limit their use of the drug.