NEW YORK (CBSNewYork) — There is new information about whether or not MRI scans are safe for pregnant women as the first large-scale study on the effect of MRI’s on mother and baby has been released.

CBS2’s Dr. Max Gomez reported there is one type of scan women should avoid: one done with an intravenous contrast agent called gadolinium.

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MRI scans are useful for any number of conditions, but especially when there’s a suspected brain tumor. However, doctors are always cautious when it comes to any kind of scan during pregnancy, especially during the first trimester when birth defects are more likely to form.

“We already have a fair amount of data on CAT scan safety in pregnancy, but MRI was lacking,” said Dr. Joel Ray of St. Michael’s Hospital in Toronto.

Ray and his hospital colleagues analyzed data from 1.5 million women collected over 12 years and concluded that MRI in the first trimester was safe for both mother and fetus.

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“The conclusion to the study related to first trimester MRI is that it appears to be safe without evident birth defects, cancer, stillbirth or death of the newborn child,” said Ray.

Sometimes MRI’s are done with an IV contrast agent called gadolinium to better show some structures. The study also included women who had gadolinium MRI scans at any point during pregnancy. These MRI’s with contrast were associated with a higher risk of fetal death and a variety of inflammatory and skin conditions in the newborn.

“It reinforces a to-date evidence-free notion that gadolinium might harm the fetus,” said Ray. “Gadolinium contrast would be best avoided in pregnancy.”

There will be times when a woman’s life or her baby’s is at risk and something like gadolinium is important to help make treatment decisions.

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For regular MRI’s, they appear to be safe for both mother and baby.