Acetaminophen Use During Pregnancy Increases ADHD Risk: Study
February 25, 2014

Acetaminophen Use During Pregnancy Increases ADHD Risk: Study

Brett Smith for - Your Universe Online

Pregnant women go through a wide range of pains throughout their pregnancy and to relieve their discomfort many of them have turned to the pain reliever acetaminophen, which has been on the market since the 1950s.

Now, a new study from an international team of researchers has found a link between a mother’s acetaminophen use during pregnancy and increased risk for her child developing attention-deficit/hyperactivity disorder (ADHD) and hyperkinetic disorder, a particularly severe form of ADHD.

Children of women who took acetaminophen had a 13 percent greater chance of showing ADHD-like behaviors by 7 years old and a 37 percent higher risk of hyperkinetic disorder.

"The causes of ADHD and hyperkinetic disorder are not well understood, but both environmental and genetic factors clearly contribute," said study author Dr. Beate Ritz, chair of the department of epidemiology at UCLA. "We know there has been a rapid increase in childhood neurodevelopmental disorders, including ADHD, over the past decades, and it's likely that the rise is not solely attributable to better diagnoses or parental awareness. It's likely there are environmental components as well."

"That gave us the motivation to search for environmental causes that are avoidable," added co-author Dr. Jørn Olsen, of the University of Aarhus' former chair of the UCLA epidemiology department. "Part of the neuropathology may already be present at birth, making exposures during pregnancy and/or infancy of particular interest. Because acetaminophen is the most commonly used medication for pain and fever during pregnancy, it was something we thought we should look at."

For the study, which was published in the journal JAMA Pediatrics, researchers used the Danish National Birth Cohort to look at pregnancy problems and diseases in offspring due to variables in early life, taking note of the side effects of medicines and infections in particular. The study included over 64,000 children and mothers who were enrolled in the Danish study between 1996 and 2002. Acetaminophen use while carrying a child was determined using phone interviews that were carried out as many as three times, both during pregnancy and six months after childbirth.

The scientists next followed up on both parents and children seven years after childbirth. In the follow-up interviews, researchers asked parents about any behavioral issues including emotional problems, conduct issues, hyperactive behavior, relationship issues and social behavior.

Researchers also pulled diagnoses of hyperkinetic disorder among the children in the study from the Danish National Hospital Registry or the Danish Psychiatric Central Registry. They also determined if ADHD medications were picked up for the children using the country's pharmaceutical prescription collection.

Over one half of all the mothers in the study said they used acetaminophen while pregnant. The scientists found that the longer acetaminophen was taken the greater the relationship between the drug and ADHD symptoms, the study team found. The danger of hyperkinetic disorder or ADHD in children was 50 percent or higher when the mothers had used the painkiller for greater than 20 weeks in their pregnancy.

"It's known from animal data that acetaminophen is a hormone disruptor, and abnormal hormonal exposures in pregnancy may influence fetal brain development," Ritz said.

"We need further research to verify these findings, but if these results reflect causal associations, then acetaminophen should no longer be considered a 'safe' drug for use in pregnancy," Olsen said.

In an accompanying editorial, scientists from Cardiff University in Wales cautioned against changing habits based on this single study.

"Findings from this study should be interpreted cautiously and should not change practice," they wrote. "However, they underline the importance of not taking a drug's safety during pregnancy for granted."