Existing evidence does not show a clear link between taking paracetamol in pregnancy and autism and ADHD in children, an in-depth review has concluded.
Researchers trawled all studies on the issue and concluded they were low quality, with "low to critically low" confidence in any findings suggesting a link.
U.S. President Donald Trump said in September that there has been a "meteoric rise" in cases of autism and that Tylenol – which is called paracetamol in the U.K. – was a potential cause.
He said the painkiller should not be taken during pregnancy, suggesting pregnant women should "tough it out."
His comments were criticized by autism campaigners and scientists in the U.K. and around the world.
Now, in a new study published in the British Medical Journal (BMJ), experts, including those from the universities of Liverpool and Birmingham, concluded that women should continue to be advised to take paracetamol when needed to treat pain and fever in pregnancy.
They said there was a "lack of robust evidence linking paracetamol use in pregnancy and autism and ADHD in offspring."
Furthermore, untreated fever, particularly in the first trimester, has been linked to an increased risk of miscarriage, birth defects and premature birth – underlining the need for women to be able to take paracetamol.
The team also suggested that any apparent link between paracetamol and autism and ADHD in previous studies may be driven by shared genetic and environmental factors within families.
For the latest study, researchers examined nine systematic reviews that included a total of 40 observational studies reporting on paracetamol use during pregnancy and the risk of autism, ADHD, or other neurodevelopmental outcomes.
All reviews reported a possible to strong association between a mother’s paracetamol intake and autism or ADHD, or both, in children, but seven of the nine reviews advised caution when interpreting the findings.
Overall, experts in the BMJ concluded that confidence in the findings of these reviews was low (for two reviews) to critically low (for seven reviews).
They added: "Existing evidence does not show a clear link between in utero exposure to paracetamol and autism and ADHD in offspring.
"Any apparent effect observed after in utero exposure to paracetamol on autism and ADHD in childhood might be driven by familial genetic and environmental factors and unmeasured confounders."
Dimitrios Siassakos, professor in obstetrics and gynecology from University College London, said: "The high-quality methodology used in this new umbrella review confirms what experts around the globe have been saying.
"The evidence that links paracetamol use in pregnancy to autism is tenuous and those studies which do report an association are confounded by the association of autism or ADHD with factors shared by families, such as genetics and lifestyle."
