No Evidence of Link Between Tylenol and Autism or ADHD, Study Confirms
In late September, when President Trump claimed that taking Tylenol during pregnancy was associated with an increased risk of autism in children, Dr. Shakila Thangaratinam knew she had to act.
Acetaminophen, the drug marketed as Tylenol, is the first-line drug to treat fever in pregnant women, and the alternatives, as the obstetrician and University of Liverpool professor knew, can be dangerous. Taking ibuprofen, a nonsteroidal anti-inflammatory drug, marketed under the name Advil, interferes with the development of the fetal cardiovascular system. On the other hand, letting the fever rage uncontrolled means exposing the fetus to harmful substances produced by the mother who is fighting her infection.
But health care providers, she knew, were likely to be inundated with questions: “Many professional organizations, in response to the American announcement, said, ‘If you’re worried, go talk to your health care professional,'” says Thangaratinam.
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Recognizing that clinicians would need clear, evidence-based guidance to reassure worried patients, Thangaratinam and colleagues undertook a comprehensive review of existing research, which they have now published in the British Medical Journal.
They found that many studies showing a link between acetaminophen and autism and ADHD do not adequately account for the fact that these diagnoses are often passed down within families. When, in a handful of better-designed studies, siblings of children with a diagnosis were included, the link weakened significantly.
Thangaratinam highlights in particular two Scandinavian studies and a Japanese study, in which a large number of families were followed. In these studies, researchers compared sibling pairs in which one child had been exposed to acetaminophen in utero and the other had not.
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“What we found was consistently [these studies]”The association that was initially present disappeared when a sibling control analysis was performed,” she says. There was no difference in diagnosis rates between these siblings, despite their different experiences during gestation.
Compiling the survey reinforced Thangaratinam’s sense that in many cases there is not enough quality information available to enable pregnant women to make informed decisions. Pregnant women are traditionally excluded from drug trials, so little is known about the effects of many common medications on pregnancy. She called it “one of the most important messages to bring forward in women’s health”: more studies focusing on drugs for pregnant women will yield better results.
