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 The statistical analysis, published in JAMA Network Open, does not
prove that having a C-section directly causes such problems. Other
factors that lead doctors to order a surgical delivery of the baby
may underlie the link.
The researchers collected studies covering more than 20 million
deliveries dating back to 1999, to create a large pool of data to
assess risks associated with cesarean delivery that may not be
evident in the smaller individual studies.
When the team, led by Tianyang Zhang of the Karolinska Institute in
Stockholm, assessed autism spectrum disorder, they looked at 29
study populations, 17 of which showed an increased risk that was
large enough to be statistically meaningful.
Among the babies of women who had vaginal deliveries, for example,
the autism rate was 0.8%, according to data provided in the paper. A
33% increase would put the rate in the cesarean group at 1.0%.
For ADHD, Zhang's group assessed 14 study populations, only 5 of
which showed a statistically significant risk with C-section, but
those studies tended to be the largest so they carried more weight.
Babies born through vaginal delivery had an ADHD rate of 2.4%. A 17%
increase in the C-section group would raise the rate by 0.4
percentage points, to 2.8%.
"The impact of this is not going to be great because the increase is
still pretty low," said Dr. Pankhuree Vandana, a pediatric
psychiatrist at Nationwide Children's Hospital in Columbus, Ohio,
who was not involved in the research.
"It's not very dramatic. It's statistically significant but from the
population standpoint, the risk is not huge," she said in a phone
interview. "And it absolutely does not prove that cesarean section
is causing autism or ADHD. The risk factors that lead to a C-section
may also be risk factors that lead to autism or ADHD."
Zhang, a PhD student at Karolinska, also emphasized in an email that
"our study does not provide irrefutable proof that C-sections CAUSE
neuropsychiatric disorders."
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For example, "C-section is often recommended by obstetricians if the
mother has diseases such as diabetes, hypertension, etc. Some of the
diseases might already have an effect on a child's brain development
when he or she is still in the womb," the author said. A combination
of factors may contribute to the risk, so "it would therefore be
wrong to demonize C-sections. C-sections should continue to be used
when medically necessary."
However, "the results appear to further add to the known adverse
health outcomes associated with cesarean delivery and suggest
judicious use of cesarean delivery," the researchers write in their
report.
There is already evidence that children born through C-section have
a higher risk of obesity, allergies, childhood diabetes and a form
of blood and bone marrow cancer known as acute lymphoblastic
leukemia.
On the other hand, surgical delivery can be lifesaving.
Still, it is widely believed that the surgery is overused in many
countries. The optimal rate is considered to be 10% to 15% but
worldwide cesarean delivery rates, which were about 6% in 1990, have
risen to 21%, according to 2015 data.
The study also found that whether a cesarean delivery was scheduled
or done on an emergency basis had no effect on the autism or ADHD
rates.
The Zhang team found hints of slightly higher rates of intellectual
disability, obsessive-compulsive disorder, tic disorders and eating
disorders among children born through C-section, but those
associations were not statistically significant, meaning they could
be due to chance.
The team did not find any link between cesarean delivery and other
conditions such as depression.
SOURCE: https://bit.ly/2zCKOkR JAMA Network Open, online August 28,
2019.
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