New issue: What really causes autism?

Our best research – studies that looked at the health records of millions of children – has, to date, found no causal link between taking acetaminophen (otherwise known as paracetamol and sold under the brand name Tylenol in the US) during pregnancy and the onset of autism. In fact, as rates of autism diagnoses have gone up, acetaminophen use during pregnancy has actually gone down. So why do some high-profile US politicians suggest otherwise? Well, there was a study, published a decade ago, that looked at data collected on almost 2,650 children, which did find an effect. But it’s possible that this research was actually observing the effect of whatever symptom the drug was meant to treat – not the drug itself. The backdrop to this row is the undeniable observation that autism diagnoses are on the rise. One in 59 children were thought to have the condition in the US in 2015; that figure is now one in 31, according to the Centers for Disease Control and Prevention (CDC). Most experts attribute this rise to improvements in identifying autism. Indeed, we’ve gotten better at understanding what autism looks like in all its forms. And therein lies some clarity. Just as we’re beginning to understand that there are different types of autism, there are likely to be several factors that can shift the dance between genetics and the environment as your brain develops during pregnancy. Timing is everything in the womb, which is why one scientist is growing tiny human brains (or at least parts of them) in a lab – to find out when and where the first signs of autism appear.

Holly Spanner

Published: March 26, 2026 at 8:00 am

The front cover of issue 431 of BBC Science Focus

Tree-top time machines

Scientists are preparing to pump thousands of tonnes of carbon dioxide into the Amazon rainforest to answer one of climate change's biggest mysteries. Will the extra CO₂ in a future atmosphere fertilise tree growth, soak up some of our emissions? Or is that hope misguided?

AI horror stories

Why you should always think twice before following anyone’s advice – especially when it comes from an AI. In this issue, we shine a light on seven failures – including one AI that decided to lie and cover up its mistakes.

Procrastination

The delaying tactics you employ to avoid tackling your to-do list might mean you have bigger issues that need addressing. Psychologists say that stress may be the culprit, but there are things you can do to minimise procrastination.

The new space race

Space was never really peaceful. Now everyone’s stopped pretending. Space may soon need to be viewed as a domain that needs to be actively defended, contested and potentially fought over.

Plus

Oral microbiomes: With new studies confirming the link between oral and overall health, it’s time to close the gap between dentistry and medicine.
Fart walks: Research into the benefits of a post-meal ‘fart walk’ is more than just hot air.
Q&A: Your questions answered. This month, our experts discuss: What’s the worst thing you can do for the planet online? Should I start using an ice roller? What’s the world’s longest oil spill? Is my dog brainwashing me for treats? Why do we root for the villain in movies? What is the ‘returning soldier effect’? What’s the most secret place scientists have locked away? Why do men tend to have worse handwriting than women? And more… And more…

Issue 431 on sale Thursday 26 March 2026

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Staff Writer, BBC Science Focus

Holly is the Staff Writer for BBC Science Focus and looks after the popular Q&A section. She holds an MSc (distinction) in Geoscience (Space and Climate Physics) from UCL, and specialises in astronomy and earth sciences. Before joining Our Media, she worked as a geoenvironmental consultant and engineer, informing on ground risk and remediation in the north of England, while hunting for exoplanets in her spare time. Alongside this, she was regional editor of a popular theatre website for nine years, and has a solid background in curating and developing content for the digital space. Holly is also an artist and illustrator, and regular contributor to the craft website, Gathered. She has previously worked with the RSPB, English Heritage, Disney, Pilot and Brother, as well as on BBC Good Food magazine, Home Style magazine, and Papercraft inspirations magazine. She enjoys photography and has a sustained interest in antiques.

Issue 431 of BBC Science Focus is on sale 26 March 2026