British researchers monitored 7,796 pairs of parents and their child. The moms were asked about their use of Tylenol both during and after pregnancy. More than half of the mothers used acetaminophen at least once during the first 18 weeks of pregnancy. The figure was 42% at 32 weeks.
The children were followed until the age of 5.
Women who used Tylenol at 18 and 32 weeks of pregnancy saw a 42% increased risk of conduct problems and a 31% higher risk of symptoms of ADHD (attention-deficit/hyperactivity disorder) in their child compared to mothers who never took acetaminophen while pregnant, the researchers reported in JAMA Pediatrics.
But put another way, mothers who took acetaminophen during the third trimester had children with only a slightly higher risk of behavioral problems compared to moms who never took the drug: 6% vs. 4%.
In addition, there was no increased risk of behavioral issues in children when Tylenol was used after pregnancy by the mother. A partner’s use of the drug during pregnancy was not associated with an increased risk.
While the results may cause some pregnant women to think twice before taking Tylenol, the study’s lead author said that fever is a common occurrence in pregnancy and acetaminophen is effective at lowering temperature. And leaving fever untreated can lead to premature birth.
“However, the risk of not treating fever or pain during pregnancy should be carefully weighed against any potential harm of acetaminophen to the offspring,” Evie Stergiakouli, PhD, of the University of Bristol, and colleagues, wrote in their journal article.