Acetaminophen, which we thought was safe, isn't all that it has been cut out to be, according to a study. New research shows that the widely used pain-relieving medication during pregnancy might lead to multiple behavioural problems in children.

Prenatal use of the drug at 18 and 32 weeks of pregnancy could lead to problems such as hyperactivity and conduct problems in children, according to the study published in the journal JAMA Pediatrics. It could lead to "emotional symptoms and total difficulties" in children.

However, the experts added that the risk of not treating pain or fever while pregnant needs to be weighed "against any potential harm of acetaminophen to the offspring."

The study was conducted by Evie Stergiakouli, Ph.D., of the University of Bristol, United Kingdom, and coauthors. They examined the information collected from almost 8,000 pregnant women and children. It was found that five percent of the children born to the participants got behavioural problems by the time they were seven.

However, refuting the claim by the authors, University of Melbourne professor of pharmacology and therapeutics, Norman Saunders, said that the study did not show any "increased risk of behavioural difficulty in children."

"The most such a study can establish is an association," he said. "It certainly cannot demonstrate an increased risk of behavioural difficulties in the children, as claimed by the authors."

Even while it is better that pregnant women should not take drugs whenever possible, there is no evidence to show that there should be more limitations on their use of paracetamol.

"They have not distinguished between different reasons why the patients were taking paracetamol. The authors did not analyse separately possible associations with the different reasons why the paracetamol had been taken; for example, this might have revealed an association with infections such as flu or cold, which would have been an alternative explanation for the problems identified in the children," Saunders added.

However, pregnant women should take care to consult the doctor before taking the drugs, and also minimise their use.