Autism spectrum disorder is a developmental disorder that affects behaviour, social interaction and learning.
Acetaminophen — also known as Tylenol (or paracetamol outside the US) — is linked to autism and ADHD, a study suggests.
Children exposed to higher levels of acetaminophen in the womb were at almost four times the risk of developing autism.
Acetaminophen was linked to almost three times the risk of attention-deficit hyperactivity disorder (ADHD) when they were tested at around nine-years-old.
Autism spectrum disorder is a developmental disorder that affects behaviour, social interaction and learning.
Classic signs of autism include more limited and repetitive play, less name response, less social smiling, less babbling and limited gesture use.
ADHD is characterised by impulsiveness or hyperactivity
and serious problems maintaining attention on one task.
Many children continue to experience the symptoms of ADHD into adulthood.
The results come from a study of 996 births in the US city of Boston.
Blood was taken from the umbilical cord and analysed for levels of acetaminophen and its byproducts.
Around nine years later 6.6 percent had been diagnosed with autism spectrum disorder and 25.8 percent with ADHD.
Researchers then compared children with the lowest levels of acetaminophen in their umbilical cord blood at birth to those with the highest levels.
The results showed that high levels of acetaminophen increased the risk of developing autism by 3.62 times.
For ADHD, those exposed to the highest levels of ADHD were at 2.86 times the risk of developing the condition.
As ever, with this type of research, though, correlation not equal causation.
However, several studies have linked acetaminophen to autism.
Professor Andrew Shennan, an obstetrician at King’s College London, who was not involved in the study, said:
“Paracetamol is a recommended drug for use in pregnancy and will be commonly used.
This type of uncontrolled study does not imply paracetamol use causes autism, as the reason for taking paracetamol may be the issue rather than the drug itself, and a mechanism for it to cause harm is not clear.”
Professor Stephen Evans, a drug safety expert, who was also not involved in the study, said:
“In general, advice has always been to avoid or limit most drugs in pregnancy if possible, but some drugs are required for a mother’s health.
Avoiding paracetamol when it is not needed is sensible and has always been the case, but millions of women with perfectly normal children will also have taken paracetamol during pregnancy.
The results of this study should not raise anxiety in pregnant women.”
The study was published in JAMA Psychiatry (Ji et al., 2019).
