Women who use acetaminophen, a common pain relief medication, during pregnancy may be exposing their children to a heightened risk of developing a number of behavioral problems, a new study has found.

Acetaminophen, commonly called paracetamol, is considered safe for pregnant women as a fever reducer. However, in the study published Monday in the journal JAMA Pediatrics, a team of British researchers highlighted possible effects of the drugs that could be detrimental to the child in the long run.

The researchers studied data for 7,796 mothers from the Avon Longitudinal Study of Parents and Children from 1991 to 1992. Data for their children and partners was also analyzed for behavioral problems and acetaminophen use.

Acetaminophen use was assessed at 18 and 32 weeks of pregnancy and when the children were 5 years of age (postnatal usage). As a part of the questionnaire, the mothers were to report of any behavioral problems in the children when they were 7 years old.

Almost 53 percent of the women reported using acetaminophen at 18 weeks while 42 percent reported usage at 32 weeks. Postnatal usage was reported by 89 percent of the women and 84 percent of their partners. Behavioral problems were reported in five percent of the children.

The women who used acetaminophen at 18 weeks of pregnancy were 42 percent and 31 percent more likely to report hyperactivity and conduct problems respectively in their children than the women who did not use the drug. Using acetaminophen at 32 weeks increased the risk of exposing the children to a wide range of behavioral difficulties by 46 percent.

To make the study’s findings more comprehensive, the researchers analyzed a number of other factors. They found no links between postnatal acetaminophen usage or usage of the drug by the partner during pregnancy and the child’s behavioral problems.

However, the findings have been questioned by some. NBC News reported Dr. Hal Lawrence of the American College of Obstetricians and Gynecologists, saying: “ACOG and ob-gyns across the country have always identified acetaminophen as one of the only safe pain relievers for women during pregnancy.”

“This new study, and other studies that have been conducted in the past, show no clear evidence that proves a direct relationship between the prudent use of acetaminophen during any trimester and developmental issues in children.”

A 2013 study had found that taking acetaminophen frequently during pregnancy could raise the risk of behavior problems in children by 70 percent. The new study does not put the figures as high as the previous one but the authors caution against the frequent usage of the pain reliever. They added that “the risk of not treating fever or pain during pregnancy should be carefully weighed against any potential harm of acetaminophen to the offspring.”