Comprehensive Study Finds No Risk of Autism or ADHD from Acetaminophen During Pregnancy

Taking paracetamol or acetaminophen (also known under the brand name Tylenol in the US) during pregnancy does not increase the risk of autism, attention deficit hyperactivity disorder (ADHD), or intellectual disability in children. This conclusion comes from the most comprehensive evaluation of the available evidence to date, published in The Lancet Obstetrics, Gynaecology & Women’s Health. The study was conducted by researchers at City St George’s, University of London.

How Acetaminophen Affects Pregnancy

The research team conducted a systematic review and meta-analysis based on the results of 43 previously published studies. Their goal was to determine whether taking paracetamol during pregnancy is safe. The analysis was prompted by renewed public concern following claims in September 2025 that prenatal exposure to paracetamol could impair brain development and increase the likelihood of autism.

These concerns were fueled by earlier studies that had found a small statistical association between paracetamol use during pregnancy and autism diagnoses. However, many of these studies had significant limitations. Some were based on incomplete data, while others did not take into account family history or genetic factors. A key gap was the lack of comparisons between siblings, which can help separate the effects of medication from inherited traits and shared environmental influences.

Why Comparisons Between Siblings are Important

To address these weaknesses, the researchers focused on the highest-quality data available. They compared pregnancies in which paracetamol was taken with those in which it was not, paying particular attention to studies that examined siblings from the same mother. In these sibling comparison studies, one child was exposed to paracetamol during pregnancy, while the other was not.

This approach allows researchers to better control for shared genetic factors, home environment, and long-term parental characteristics. These factors are difficult to fully account for in traditional observational studies, but can greatly influence a child’s development.

The data from the sibling comparison was extensive. The researchers analyzed the results of 262,852 children who were tested for autism, 335,255 children who were tested for ADHD, and 406,681 children who were tested for intellectual disability. In these large groups, there was no evidence that taking paracetamol during pregnancy increased the risk of any of these conditions compared to pregnancies in which the drug was not taken.

Researchers Explain the Findings

Professor Asma Khalil, professor of obstetrics and maternal-fetal medicine at City St George’s, University of London, and a consultant obstetrician, led the study and addressed why previous research may have caused alarm. “Our findings suggest that previously reported associations are more likely to be explained by genetic predisposition or other maternal factors such as fever or underlying pain rather than a direct effect of paracetamol itself.

“The message is clear: paracetamol remains a safe option during pregnancy when taken according to the instructions. This is important because paracetamol is the first-choice medication we recommend to pregnant women for pain or fever. They should therefore be confident that they still have a safe option for relieving their symptoms.”

Strict Quality Controls and Remaining Limitations

Each study included in the analysis was assessed using the QUIPS (Quality In Prognosis Studies) tool, which evaluates various aspects of study design to assess the risk of bias. The lack of association between paracetamol use during pregnancy and autism, ADHD, or intellectual disability remained even when the researchers limited their analysis to studies with low potential for bias (and therefore of the highest quality). The same reassuring results were observed in studies that followed children for more than five years. The authors also pointed out some limitations. There was not enough consistent data to examine whether the risks differed depending on the trimester of exposure, gender of the baby, or frequency of paracetamol use. Too few of the existing studies comparing siblings reported these details.

What this Means for Pregnant Women

Overall, the findings are consistent with the guidelines of major medical organizations worldwide. The researchers hope that this thorough review will help to dispel any remaining doubts about the use of paracetamol during pregnancy. Not treating severe pain or fever can pose known risks to both mother and child, especially if the mother’s fever is left untreated. These findings support the continued use of paracetamol as a safe option when taken according to the instructions. It remains important that pregnant women always talk to their doctor first before taking any medicines!