Paracetamol use during pregnancy not linked to autism, our study of 2.5 million children shows

United States President Donald Trump recently claimed that using the common painkiller acetaminophen (also known as paracetamol and by the brand name Tylenol in the US) during pregnancy is fuelling the rise in autism diagnoses. He then went on to suggest pregnant women should “tough it out” rather than use the common painkiller if they experience fever or pain.

This announcement has caused alarm and confusion worldwide. But despite Trump’s claim, there is no strong scientific evidence to back it up. Our study of nearly 2.5 million births in Sweden published in 2024 shows no evidence that acetaminophen use during pregnancy increases a child’s risk of autism. This is the largest study conducted on the subject to date.

To understand whether acetaminophen really poses a risk in pregnancy, we turned to Sweden’s national health registers, which are among the most comprehensive in the world. Our study followed nearly 2.5 million children born between 1995 and 2019, tracking them for up to 26 years.

Using prescription records and interviews that midwives conducted during prenatal visits, we could see which mothers reported using acetaminophen (about 7.5% of pregnancies) and which did not.

We also made sure to account for any variables that may have affected the results of our statistical analysis – including controlling for health factors, such as fever or pain, which would have influenced whether or not a mother used acetaminophen during her pregnancy. This was to ensure a more fair comparison between the two groups.

We then looked at the children’s neurodevelopmental outcomes – specifically whether they were diagnosed with autism, ADHD or an intellectual disability.

The real strength of our study came from being able to compare siblings. This allowed us to compare children born to the same mother, where acetaminophen had been used during one child’s pregnancy but not the other. We compared over 45,000 sibling pairs, where at least one sibling had an autism diagnosis.

This sibling design is powerful because siblings share much of their genetics and family environment. This allows us to tease apart whether the drug itself – rather than underlying family traits or health conditions – is responsible for any apparent risks for neurodevelopmental outcomes.

Paracetamol use during pregnancy not linked to autism, our study of 2.5 million children shows

Our research provides strong evidence against the concerning claims made recently by US president Donald Trump.

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