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 But when the expectant mother has an MRI with gadolinium contrast, a
material that makes it easier to see internal structures like blood
vessels in the brain, risk for stillbirth, neonatal death or the
child having any of several serious health conditions may rise,
researchers say.
“We know that MRI is actually being encouraged as the main high
fidelity method of imaging in women of reproductive age,” since it
does not involve radiation, and produces outstanding images of
deeper cavities that ultrasound can’t get at, said lead author Dr.
Joel Ray of St. Michael’s Hospital and the Institute for Clinical
Evaluative Sciences in Toronto.
The new results “invigorate or support” what most people believed by
intuition or smaller datasets: that non-contrast MRI is generally
safe for pregnant women, Ray told Reuters Health.
With contrast MRIs, negative outcomes are still very rare but it may
be a good idea to avoid these MRIs in pregnancy, or when a woman may
be pregnant, he said.
The researchers analyzed more than 1 million births between 2003 and
2013 in Ontario, Canada, using universal healthcare databases. About
one in 250 women had undergone an MRI during pregnancy, one in 1,200
during the first trimester and one in 3,000 with gadolinium
contrast. Health of the babies was followed from birth until they
were 4 years old.
Having an MRI during the first trimester was not tied to an
increased risk of stillbirth, newborn death, cancer, congenital
defects or hearing loss in the children.
Only 397 women had gadolinium contrast MRIs during pregnancy,
compared to more than 1.4 million without any MRI in this
comparison.
Connective tissue or infiltrating skin conditions like nephrogenic
systemic fibrosis were about 36 percent more common in babies born
to the gadolinium group than the no-MRI group, according to the
results in JAMA. More broadly, rheumatological and inflammatory
conditions were similarly increased by about 45 cases per 1,000
children per year.
There were seven stillbirths or newborn deaths in the gadolinium
group compared to 9,844 in the no-MRI group, so while still rare,
these outcomes were twice as common in the gadolinium group, the
authors note.
An adult body processes and clears gadolinium contrast materials
through the urine, but a fetus exposed via the placenta will
continually urinate and ingest the same material in the amniotic
fluid until birth, Ray said.
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“The theory was that you can recirculate gadolinium over and over
again, and this brings that theory a little bit closer to a clinical
point,” he said.
Gadolinium can usually be avoided during pregnancy, but “in a woman
who is pregnant, if she really needs gadolinium then she’s the
priority,” he said.
“Potential risk versus benefit should always be assessed when an
imaging study is recommended,” said Dr. Dorothy Bulas, professor of
pediatrics and radiology at George Washington University School of
Medicine and Health Sciences in Washington, D.C. “This study is
reassuring and helps support the use of MRI at any gestation if
there is a valid indication for the exam,” she said by email.
“The study also supports the need to avoid gadolinium in the
pregnant patient unless the maternal benefits truly outweigh the
potential fetal risks that were noted in this large study cohort,”
Bulas added.
Current contrast media guidelines already incorporate appropriate
safety concerns, said Dr. Karen Oh of Oregon Health and Sciences
University in Portland, who was not part of the new study.
“Doctors should continue to provide appropriate prenatal care and
utilize MRI when indicated; and women should ask and receive
explanations for indications for studies during pregnancy, have
their questions answered appropriately, so that they can feel
comfortable with the care they are receiving,” Oh told Reuters
Health by email.
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