When you’re pregnant, there is already so little medication you can take to relieve basic aches and pains. But this latest research suggests that even acetaminophen, an extremely common pain med taken by expectant mothers, may have adverse effects on unborn children.

“A new study has found that paracetamol (acetaminophen), which is used extensively during pregnancy, has a strong association with autism spectrum symptoms in boys and for both genders in relation to attention-related and hyperactivity symptoms,” reports Science Daily.

Paracetamol, more commonly known as acetaminophen, is marketed in Canada under the brand name Tylenol and in the U.K. as Panadol. It’s considered one of the most widely used pain killers in the world, which is why this finding of this study is cause for concern for both researchers and soon-to-be mothers.

“This is the first study of its kind to report an independent association between the use of this drug in pregnancy and autism spectrum symptoms in children.”

The study looked at 2,644 kids across Spain over a five-year period, evaluating children at age one and then again at age five. Of these, around 40 per cent were exposed to acetaminophen during the first 32 weeks of pregnancy. The age five results showed that those who were exposed were more likely to be show signs of hyperactivity or impulsivity symptoms. Those who were persistently exposed “showed poorer performance on a computerised test measuring inattention, impulsivity and visual speed processing.”

“Although we measured symptoms and not diagnoses, an increase in the number of symptoms that a child has, can affect him or her, even if they are not severe enough to warrant a clinical diagnosis of a neurodevelopmental disorder,“ explained lead author of the study Claudia Avella-Garcia, a researcher at CREAL, an ISGlobal allied centre in Barcelona.

Researchers also noticed that these findings were particularly true for boys.

"The male brain may be more vulnerable to harmful influences during early life,” said Avella-Garcia. “Our differing gender results suggest that androgenic endocrine disruption, to which male brains could be more sensitive, may explain the association.”

But with Tylenol being considered safe for pregnant women for so long, these findings have prompted scientists to dig deeper to find out what exactly is causing this outcome.

“Paracetamol could be harmful to neurodevelopment for several reasons,” explains co-author Dr. Jordi Júlvez, also a researcher at CREAL. “First of all, it relieves pain by acting on cannabinoid receptors in the brain. Since these receptors normally help determine how neurons mature and connect with one another, paracetamol could alter these important processes. It can also affect the development of the immune system, or be directly toxic to some fetuses that may not have the same capacity as an adult to metabolize this drug, or by creating oxidative stress.”

That said, both Avella-Garcia and Júlvez stressed that further research needs to be conducted in order to better understand these findings.

What do you think of this recent study? Should expectant mothers consider this cause for concern? Let us know your thoughts by tweeting to @YahooStyleCA.