Pregnant women should exercise caution when taking paracetamol, also known as acetaminophen or Tylenol in the US, and only do so under the advice of a doctor, Harvard scientists have warned. This recommendation stems from growing concerns that the common painkiller could increase the risk of autism and Attention Deficit Hyperactivity Disorder (ADHD) in their children.

While paracetamol is widely used by expectant mothers for pain, headaches, and fever, numerous studies have previously indicated a correlation with higher rates of autism and ADHD. A recent analysis by US researchers from Mount Sinai and Harvard's School of Public Health, encompassing over 100,000 individuals, is being hailed as the most comprehensive to date. This study provides what its authors describe as the 'strongest evidence so far' of a link, urging mothers-to-be to use paracetamol sparingly, recommending 'the lowest effective dose for the shortest possible time.'

It is crucial to note that the research team emphasized that these findings establish an association rather than direct causation between the drug and neurodevelopmental disorders. However, they deem the consistency and implications of this association significant enough to warrant further investigation. Dr. Diddier Prada, assistant professor of population health science at Mount Sinai Hospital and co-author, highlighted that 'higher-quality studies are more likely to show a link between prenatal acetaminophen exposure and increased risks of autism and ADHD.' He added that 'given the widespread use of this medication, even a small increase in risk could have major public health implications.'

Despite these warnings, Dr. Prada stressed that pregnant women should not abruptly cease taking medication without consulting their healthcare providers, as untreated pain or fever can also pose risks to the baby. He advised discussing the safest approach with doctors and considering non-drug alternatives whenever feasible. Currently, the NHS in the UK recommends paracetamol as the 'first choice' painkiller for expectant mothers, but strictly for short durations and at the lowest effective dose. Approximately half of pregnant women in the UK and around 65 percent in the US use paracetamol, with health authorities typically advising extra caution only for those with specific conditions like liver or kidney disease or those on epilepsy medication.

The US researchers reached their conclusions after reviewing 46 separate studies, involving more than 100,000 participants. They meticulously collected data on when paracetamol was taken—whether in the first, second, or third trimester, or throughout the entire pregnancy—and cross-referenced it with mothers' medical records. Publishing their findings in the journal Environmental Health, they concluded that 'Ultimately, the obtained scores suggest strong evidence of a likely relationship between prenatal acetaminophen use and increased risk of ADHD in children.' They further stated, 'This includes high-quality studies that provide very strong evidence of an association and studies that provide strong evidence of an association.' Similarly, they found 'strong evidence of a relationship between prenatal acetaminophen use and increased risk of autism in children.'

These findings emerge amidst a surge in demand for autism assessments, reaching record levels in the wake of the Covid-19 pandemic. NHS figures from December 2024 revealed nearly 130,000 under-18s in England were awaiting assessment, a situation experts have labeled an 'invisible crisis' due to services struggling to meet rising demand. Autism, a spectrum condition present from birth, varies widely in its manifestation, with some individuals requiring minimal support while others need full-time care.

Concurrently, NHS figures indicate that over 230,000 people in England are now prescribed ADHD medication for symptoms like inattention and hyperactivity. Prescription rates escalated by a fifth last year, marking the sharpest annual increase since records began in 2015. This surge is predominantly driven by women in their 20s and 30s, although prescriptions for children are also rising. While some experts express concern about potential over-diagnosis and the liberal dispensing of powerful stimulant drugs by private clinics, others contend that many adults are only now receiving the long-overdue help they need, especially given that ADHD was only formally recognized in the UK as a disorder persisting into adulthood in 2008.

In the US, an estimated 2.3 million children and seven million adults are diagnosed with Autism Spectrum Disorder (ASD). Diagnoses have increased sharply over the past two decades; the Centers for Disease Control and Prevention reported that in 2000, approximately 1 in 150 children received an ASD diagnosis, a figure that climbed to 1 in 31 by 2020. This near-quadrupling reflects both enhanced awareness and evolving diagnostic criteria. A 2024 study analyzing 12.2 million Americans' health records further highlighted a 175 percent increase in autism diagnoses over an 11-year period. The debate continues among researchers, with some attributing the rise to expanded screening and reduced stigma, while others suggest that biological and environmental factors may also play a role.