Safety of Tylenol in pregnancy still backed by Canadian medical groups

The ruff governing body is widely expected to do a disputed nexus betwixt autism and the use of Tylenol in pregnancy — one that is being closely watched by doctors and scientists.

Speaking to reporters on Sunday night, U.S. President Donald Trump teased a Monday announcement, saying "I think we found an answer to autism."

A White House event is scheduled for 4 p.m. ET.

U.S. Health Secretary Robert F. Kennedy Jr. Promised earlier this year to determine the cause of autism by September, baffling experts who say there is no single cause and that the rhetoric appears to ignore decades of science into the genetic and environmental factors that can play a role.

Autism spectrum disorder is a lifelong developmental condition that presents with a range of symptoms that can include delays in language, learning and differences in social or emotional skills. Individuals with autism can also have a wide range of support needs.

The prevalence is about two per cent in Canadian children and youth, according to the Public Health Agency of Canada. 

Autism is mostly rooted in genetics, with several hundred inherited genes thought to play a role, even if the parent shows no signs of autism. Mutations can occur as the brain is developing and cells rapidly divide. 

Different combinations of genes and other factors can all affect how a fetal brain develops.

Autism rates have been going up for decades for two main reasons.

First, the definition of autism broadened as scientists expanded their understanding of its wide range of traits and symptoms. That led to changes in the criteria doctors use to diagnose autism and improvements in screening.

At the same time, parents increasingly sought a diagnosis as autism became better known and schools began offering educational services they hoped could help their kids.

There is no single test for autism, which is diagnosed mostly through developmental and behavioural assessments, making it hard to tell if there may be additional factors behind the increase.

The Wall Street Journal, the Washington Post and Politico have all reported that the Trump administration plans to link autism to the use of the painkiller Tylenol, or acetaminophen, in pregnancy. 

Last week, the Society of Obstetricians and Gynaecologists of Canada (SOGC) reaffirmed "acetaminophen remains a safe and appropriate first-line option for managing fever and pain during pregnancy when medically needed, at recommended doses and for the shortest duration necessary."

The SOGC's position is based on its review, finding no causal evidence linking prenatal exposure to acetaminophen and neurodevelopmental disorders like autism spectrum disorder and ADHD. 

"Pregnant women shouldn't feel guilty about using the medication," Dr. Graeme Smith, editor and chief of the Journal of Obstetrics and Gynaecology Canada, said Monday.  That goes for past and current pregnancies, he added. 

Last year, a well-designed population-based study of more than two million children in Sweden focused on siblings whose mothers took acetaminophen in one of their pregnancies, compared with no use of acetaminophen.

"In these sorts of sibling analyses, any association just completely went away, which implies that a mother's factors, like genetics, are actually responsible for the statistical association," said Brian K. Lee, a corresponding author of the Swedish study and a professor of epidemiology at Drexel University in Philadelphia.

Such studies only point to associations — or two things that happen to occur at the same time, and not whether taking the pain- and fever-relief drug caused a child's disorder.

Ian Douglas, a professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, called the data in the Swedish study extremely high quality and unlikely to be improved on elsewhere. 

The SOGC and its American counterpart, the Society for Maternal-Fetal Medicine (SMFM), also offer one big caution: Untreated fevers in pregnancy, particularly the first trimester, increase the risk of miscarriage, preterm birth and other problems. 

Tylenol's label advises women to ask their doctor about use in pregnancy, and both the SOGC and the SMFM continue to advise that it's an appropriate option to treat fever and pain during pregnancy.

Older studies and reviews faced difficulties teasing apart many possible associations, like whether the reason a person took acetaminophen during pregnancy, such as for chronic pain, was what was actually behind the link, rather than the drug itself. 

Beyond genetics, the age of a child's father, preterm birth and whether the mother had certain health problems during pregnancy — such as fevers, infections or diabetes — can also play a role. 

Any concern that vaccines, including the measles vaccine, could be linked to autism has long been debunked by doctors, scientists and leading advocacy groups for people with autism.

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