A contentious debate is ongoing within the US government regarding the safety of paracetamol (known as acetaminophen or Tylenol in America) use during pregnancy, despite a comprehensive review published in the renowned medical journal, The Lancet, which found no evidence to support claims linking it to autism and ADHD. Last week, The Lancet published new research that debunked earlier assertions, notably from US officials like President Trump, who had previously claimed the common painkiller could impede brain development in unborn children.

The Lancet review, welcomed by many health experts globally, concluded that paracetamol should continue to be the primary painkiller for pregnant women. The experts behind the review highlighted that the discussion surrounding the over-the-counter medicine had become 'politicised,' leading to 'confusion' for both expectant mothers and healthcare professionals.

However, the US Department of Health and Human Services has since reiterated its concerns. A department spokesman, Andrew Nixon, referenced previous comments from Dr. Andrea Baccarelli, dean of the Harvard School of Public Health, suggesting a 'casual relationship' between paracetamol use in pregnancy and neurodevelopmental disorders. Dr. Baccarelli, a leading environmental health researcher, has examined these associations using observational studies, which differ from clinical trials. Such research fueled a broader scientific debate, cited by US health secretary Robert F Kennedy Jr. and Trump in September, who attributed the 'meteoric' rise in autism diagnoses to the drug, a conclusion strongly disputed by many scientists.

Sources close to the administration also indicated to the Daily Mail that the authors of The Lancet review may have failed to consider all relevant evidence. US health officials have consistently challenged the findings of the 'gold-standard' review, which indicated no significant link between paracetamol use during pregnancy and neurodevelopmental conditions like autism.

The obstetricians conducting The Lancet review analyzed 43 studies exploring potential connections between paracetamol use in pregnancy and conditions such as autism. They particularly emphasized sibling studies, which compare siblings from the same family, to mitigate the influence of genetics and family background, as autism and ADHD are known to be hereditary. By comparing siblings with differing in-utero exposure to paracetamol, researchers aimed to isolate the drug's specific impact. This rigorous methodology led them to conclude 'no significant link' between paracetamol use in pregnancy and autism. Other experts praised the review's 'strong and reliable' and 'rigorous methods'.

Conversely, Dr. Jay Bhattacharya, director of the National Institutes of Health, has previously criticized sibling studies as 'naive' and 'oversimplified,' arguing they can be incorrect. He noted that such studies inherently exclude families where all children had identical exposure, potentially overlooking large population segments and underestimating risk.

In response to such criticisms, Professor Asma Khalil, Professor of Obstetrics and Maternal Fetal Medicine at City St George's, University of London, and the lead of The Lancet review, stated, 'Our review does not exclude evidence; rather, it systematically evaluates all available studies and gives greater weight to those designs that are best able to address bias and confounding, which is standard practice in evidence-based medicine.' She added that earlier associations between paracetamol and neurodevelopmental outcomes have been consistently weakened or eliminated when more robust methods, including sibling-comparison studies, are utilized to account for shared genetic and environmental factors. Professor Khalil affirmed, 'Our conclusions are based on consistency across multiple rigorous analyses, not on any single study,' concluding that the review 'provides reassurance rather than alarm, and it supports current clinical guidance that paracetamol remains an appropriate first-line treatment for pain and fever in pregnancy when used as recommended.'

Paracetamol has long been considered safe and effective for expectant mothers. Approximately half of all pregnant women in the UK and about 65 percent in the US use paracetamol to alleviate pain, headaches, and fever. The debate continues against a backdrop of a significant increase in autism diagnoses, with numbers surging by nearly 800 percent over the past two decades, making more than one in 100 people in the UK autistic, according to the National Autistic Society.