Paracetamol, one of the world’s most widely used painkillers, may not be as safe during pregnancy as long believed, new research suggests.

A study published on August 14 in BMC Environmental Health analysed data from 46 previous studies involving more than 100,000 participants. The findings indicate that babies exposed to paracetamol (also known as acetaminophen or Tylenol) in the womb could face a higher risk of developing neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).

While the study highlights a possible link, researchers clarified that it does not prove paracetamol directly causes autism or ADHD. Instead, it raises concerns that prolonged or frequent use during pregnancy may play a role.

In the UK, the NHS currently advises that paracetamol is generally safe during pregnancy when used responsibly. However, the study’s authors urged moderation and medical supervision, recommending the lowest effective dose for the shortest necessary time.

Dr. Andrea Baccarelli of the Harvard T.H. Chan School of Public Health, one of the senior authors, explained:

“We recommend careful use under medical guidance, tailored to individual needs rather than broad restrictions.”

Autism is a developmental condition that affects communication, behaviour, and social interaction, while ADHD is linked to hyperactivity, poor concentration, and impulsiveness.

The findings build on earlier research, including a Nature Mental Health study published in February, which also linked foetal exposure to paracetamol with higher ADHD risks. Alarmingly, studies show that over 70% of pregnant women use the drug to relieve pain or fever.

Experts caution that untreated maternal fever or severe pain can also harm unborn babies, meaning paracetamol remains an important option. However, this new evidence may push doctors to reconsider prescribing habits and encourage expectant mothers to discuss safer alternatives or limits with their healthcare providers.