Prolonged Acetaminophen Use During Pregnancy Increases Autism, ADHD Risk, Study Finds

A new study shows taking the pain reliever acetaminophen for prolonged periods during pregnancy raises the risk of autism and ADHD. Acetaminophen is an active ingredient found in many over the counter medicines, such as Tylenol, to help relieve pain and reduce fever. Percocet and Vicodin are prescription medications containing acetaminophen. 

The research, conducted by the Hebrew University of Jerusalem, appears in the American Journal of Epidemiology. It is the most comprehensive study ever conducted on the possible association between excessive acetaminophen use during pregnancy and the autism spectrum disorder or attention deficit hyperactivity disorder.

It shows that prolonged exposure to acetaminophen during pregnancy is associated with 20% increase in relative risk for ASD and a 30% increase in relative risk for ADHD compared to those who did not take acetaminophen during pregnancy.

The research looked at more than 130,000 mother and child pairs for up to 11 years. 

It's important to note that the study looked at prolonged use, and study authors emphasize there does not appear to be any risk associated with short-term acetaminophen use during pregnancy.

The Hebrew University of Jerusalem said in a statement, "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 a fever and/or pain, acetaminophen can be taken for a short period, and if the fever or pain continues beyond that, she should consult her physician regarding further treatment."

Acetaminophen is one of the most common medications used for the 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.