Women who take the common pain reliever acetaminophen, also known as paracetamol, during pregnancy may be more likely to have children with behaviour problems than those who don’t use the drug, a British study suggests.

Researchers analysed survey data from about 7,800 mothers and found more than half of them took acetaminophen at some point during pregnancy.

Overall, about 5 percent of their children had behaviour problems by age 7. The odds of hyperactivity, conduct issues and emotional problems were all higher among the offspring of women who reported using acetaminophen while pregnant, the study found.

This doesn’t necessarily mean pregnant women should avoid taking acetaminophen, however, said lead study author Evie Stergiakouli of the University of Bristol in the UK.

“It is still appropriate to use acetaminophen during pregnancy because there is a risk of not treating fever or pain during pregnancy,” Stergiakouli said by email. “Other pain medications are not considered safe to use during pregnancy.”

The study doesn’t prove acetaminophen directly causes developmental issues in children, noted Dr Hal Lawrence, executive vice president and chief executive of the American College of Obstetricians and Gynecologists (ACOG).

"Behavioural disorders are multifactorial and very difficult to associate with a singular cause,” Lawrence, who wasn’t involved in the study, said by email. “The brain does not stop developing until at least 15 months of age, which leaves room for children to be exposed to a number of factors that could potentially lead to behavioural issues.”

To explore the connection between prenatal acetaminophen use and behaviour issues in children, researchers examined data on how many women reported taking the drug at 18 weeks and 32 weeks of pregnancy as well as when their children were 5 years old. They also looked at acetaminophen use by the women’s partners.

At 18 weeks of pregnancy, 4,415 mothers, or 53 percent of them, reported using acetaminophen, as did 3,381 mothers, or 42 percent, at 32 weeks.

When the kids were 5 years old, more than 80 percent of the women and their partners used acetaminophen. The study didn’t find any association between postnatal use of the drug by either parent and behaviour issues in children, or any link based on whether the partners took the drug while women were pregnant.

Because the associations weren’t observed in these instances, the authors conclude that behavioural difficulties in children might not be explained by unmeasured behavioural or social factors linked to acetaminophen use.

Limitations of the study include the lack of data on the dosage or duration of acetaminophen use, the authors note in Jama Pediatrics. The study also relied on parents to accurately recall and report on their acetaminophen use and on any behaviour issues observed in their kids.

While there are a few other studies that have also suggested a possible association between prenatal acetaminophen use and neurological and developmental issues in children, none of this research offers conclusive proof that the drug is the cause of the problems, noted Dr Aisling Murphy, a researcher in obstetrics and gynecology at the University of California, Los Angeles.

“Having said that, generally, our advice would be to avoid any unnecessary exposure to medications, including acetaminophen during pregnancy,” Murphy, who wasn’t involved in the current study, said by email.

“If treatment with acetaminophen is needed for pain control then taking the minimum effective dose and avoiding multiple prolonged exposures is the prudent thing to do,” Murphy added. “If pain is more severe then talking to your doctor is the next best step.” - Reuters Health