US President Donald Trump said in September there had been a “meteoric rise” in cases of autism and that Tylenol, which is called paracetamol in Ireland, was a potential cause.
He said the painkiller should not be taken during pregnancy, suggesting pregnant women should “tough it out”.
His comments were criticised by autism campaigners and scientists.
Experts said they hoped the latest study would “bring the matter to a close”.
Researchers conducted a wide-reaching review on the topic, which has been published in the journal The Lancet Obstetrics, Gynaecology and Women’s Health.
An international team of academics searched research databases for all studies reporting risk estimates for autism, attention-deficit hyperactivity disorder (ADHD) and intellectual disabilities.
Studies deemed eligible for the review compared pregnancies with and without paracetamol-exposure, as well as looking at validated questionnaires or medical records on medical outcomes.
They also looked at other ailments mothers had and the other treatments they received.
Some 43 studies were included in a systematic review, an overarching review of the data, and 17 studies in the meta-analysis – a research method for systematically combining findings from multiple studies.
A number of so-called sibling comparison studies were also included.
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