Experts shared with the Daily Mail that this divide can largely be attributed to differences in the definition and diagnosis of autism, alongside a more open approach in the US, rather than factors like medications or pollutants, as suggested by Health Secretary Robert F Kennedy Jr. and President Donald Trump. On Monday, during a press conference, the president and senior health officials warned expectant mothers against taking Tylenol or acetaminophen, citing an increased risk of autism in their children. However, experts indicated that this is not the full story and pointed out that factors like America’s higher obesity rates and the declining drug epidemic might also contribute.

The increasing number of older mothers, as pregnancy over 30 is associated with a higher autism risk, may also play a part. Dr. Jeff Singer, a senior fellow at the Cato Institute’s Department of Health Policy Studies, explained, “There is no reason why people in the UK or Canada or Australia should be any different from those in the US. Much of it concerns the practice of medicine and the different health systems in place.”

During a broad question and answer session, Trump also addressed the apparent disparity in autism rates between the US and other countries, remarking, “I hear Cuba doesn’t have it [Tylenol] because it is very expensive. They don’t have Tylenol, and I hear they have essentially no autism.” A 2022 study indicated Cuba has an autism rate of 2 to 4 per 10,000 in certain areas. Experts advise, however, that these statistics likely represent under-diagnosis due to limited monitoring in the country. While acetaminophen, known as paracetamol locally, is offered to pregnant women in Cuba, it is often in short supply.

Autism is a neurodevelopmental disorder that influences communication, interaction, and experience of the world. In the 1970s, diagnoses were limited to individuals with severe communication struggles, often facing challenges in speaking and interacting. In recent years, the definition has expanded to encompass restricted interests, repetitive behaviors, and difficulties in reading social cues. As a result of these changes, many nations have seen an increase in autism rates, with boys being more than twice as likely to be diagnosed compared to girls.

Nonetheless, experts highlight that the increase has been notably more significant in the US, which employs an even broader autism definition than Europe. While most European nations use the ICD-11 definition, requiring both persistent social interaction problems and a range of repetitive behaviors, the US employs the DSM-5 system. This system is less stringent, diagnosing patients with autism based on a single behavior. Consequently, Dr. Singer noted that children diagnosed with autism in the US might not receive the same diagnosis if assessed under European standards.

The US also has much stricter screening for autism, with American children funneled through an extensive safety net, with teachers, school counselors and pediatricians all routinely checkING for signs of the condition. The American Academy of Pediatrics recommends that all children be screened for autism at age 18 and 24 months. In many European countries, however, experts say the monitoring is not as tight and there are fewer opportunities to catch children who may be on the spectrum. Neither the UK, Germany or France have universal screening guidelines in place for autism, with British doctors told only to have children checked for the condition if concerns are raised by parents.

Experts also pointed to divides between the US and broader European population to potentially explain the different rates of autism. America has a much higher obesity rate, at 40 percent of adults, compared to European countries, with it being 26 percent in the UK, 20 percent in Germany and 17 percent in France. And this has carried over into pregnant women, with a 2024 study estimating 18.7 percent of pregnant women were obese in North America compared to 12.1 percent in Europe.

Obesity during pregnancy is already known to raise the risk of stillbirths and heart defects in babies. It also raises the risk of gestational diabetes in mothers, which may also cause infants to have an enlarged heart or experience problems during birth. But studies have also drawn a link between having an obese mother and a child being more likely to develop autism. A 2024 paper from Australia, for example, warned that mothers who were obese during pregnancy had twice the risk of having a child with autism compared to those who were not obese.

Dr Randa Jaafar, a pain specialist in New York City, said: ‘Obesity influences how the brain develops and the blood sugar regulation as well. If blood sugar is high, even if it hasn’t tipped over into diabetes yet, that could all affect the infant’s brain.’ Some experts also suggested to Daily Mail that rising maternal ages could be behind the higher rates of autism in young adults. Several studies have already linked pregnancy after 30 to a higher risk of autism in an infant, with those who have a baby after age 40 said to have an up to 81 percent higher risk of having a child with autism compared to mothers in their late 20s.

It isn’t clear why this is the case, but scientists have suggested this may be linked to the added time meaning mothers have been exposed to more environmental toxins, like pollutants or heavy metals, that could damage DNA in the egg cell raising the risk. Dr Singer said: ‘We’ve known for decades that in the mid-30s there is a much greater risk of chromosomal abnormalities and autism, particularly in women over 35. In the US, in 2023, one in five pregnancies were women over 35, that has got to play a role.’ Data does suggest, however, that both American and European mothers are becoming older at roughly the same rate.

In the US, women aged 30 to 39 years account for the largest share of births, at 47 percent of all live births, while four percent of births are to women aged 40 years and over. In the EU, for comparison, estimates suggest that over half of births were to women aged 30 years and older while about six percent of births were to women aged 40 years and older. Experts pushed back on claims that taking Tylenol, or acetaminophen, was raising the risks of autism in children, however.

The drugs are widely used on both sides of the Atlantic, known as paracetamol in the UK, and a number of studies have suggested a link between the two conditions. But others have also claimed there is no connection. Dr Singer said: ‘This is a reasonable question to ask. We know that there are many substances that can cause issues during pregnancy; no one is denying that. ‘American experts surveyed the literature and they pointed out that everything was a trade-off; a high fever during pregnancy is also risky. ‘I would say that it is unhelpful to have the federal government weight in on this. We are on this, we are investigating, my message to politicians is please for them to not get involved.’