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New important information regarding MRI’s and pregnancy. Original article linked here.

Lara C. Pullen, PhD

September 08, 2016

Women exposed to magnetic resonance imaging (MRI) during the first trimester of pregnancy do not experience an increased risk for harm to the fetus relative to women who were not exposed. The reassuring data extend through early childhood.

However, undergoing a gadolinium MRI at any point during pregnancy was associated with an increased risk for a broad range of medical conditions in young children, including rheumatological, inflammatory, or infiltrative skin conditions. Gadolinium MRI was also associated with an increased risk for stillbirth and neonatal mortality.

Joel G. Ray, MD, from the Department of Medicine and the Department of Obstetrics and Gynecology, St Michael’s Hospital, Toronto, Ontario, Canada, and colleagues published the results of their database analysis in the September 6 issue of JAMA. Theirs is the first controlled study to evaluate the effects of first trimester MRI in human pregnancy. The investigators were able to follow approximately half the children through age 4 years.

“The current findings inform published recommendations about the safety of MRI in the first trimester of pregnancy,” the authors write. “Until further studies are done, these findings suggest that gadolinium contrast should be avoided during pregnancy.”

The investigators reviewed the records of 1,424,105 deliveries of women in Ontario who received universal healthcare. This included all births from pregnancies that lasted a minimum of 21 gestational weeks.

The researchers felt confident that they were able to fully ascertain MRI exposure, as all women who receive MRI testing in Ontario have the MRI test billed under the universal system. The investigators were unable, however, to determine whether the woman’s pregnancy status was known at the time of the MRI exposure.

The overall rate of MRI was 3.97 per 1,000 pregnancies. The relative risk for stillbirth or neonatal death was 1.68 (95% confidence interval [CI], 0.97 – 2.90) in mothers receiving MRI. This translated into an adjusted risk difference of 4.7 per 1000 person-years (95% CI, −1.6 to 11.0).

In contrast, mothers receiving gadolinium MRI had a relative risk of 3.70 (95% CI, 1.55 – 8.85) for stillbirth and neonatal death, which translated into an adjusted risk difference of 47.5 per 1000 pregnancies (95% CI, 9.7 – 138.2). Gadolinium exposure was not associated with increased risk for congenital anomalies.

When the investigators compared gadolinium MRI with no MRI, the relative risk for any rheumatologic, inflammatory, or infiltrative skin condition was 1.36 (95% CI, 1.09 – 1.69), for an adjusted risk difference of 45.3 per 1000 person-years (95% CI, 11.3 – 86.8).

“We can’t be sure that these conditions that were placed under that broad array of outcome were really reflective of gadolinium exposure itself,” explained Dr Ray in a recorded author interview. The authors also acknowledge in the article that the study was underpowered to identify uncommon outcomes.

Although pregnant women regularly receive MRIs, experts have noted that the MRI uses radiofrequency fields that can heat tissues, and thus possibly damage the developing fetus. There is also concern that the loud acoustic environment may be harmful to the neonate.

Gadolinium is occasionally recommended as an intravenous contrast medium to improve the diagnostic accuracy of the MRI.

The authors have disclosed no relevant financial relationships.

JAMA. 2016;316:952-961. Full text

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