Is an MRI safe during pregnancy?

What does the evidence say about MRI scans during pregnancy?

1. Non-contrast MRI doesn't rely on radiation, and current guidance considers it to carry no known risk to the fetus at any stage of pregnancy, a real shift from older advice that once avoided it in the first trimester. 1
2. A study following more than 1,700 pregnancies exposed to MRI in the first trimester did not find a higher chance of birth defects, and several smaller studies haven't found effects on fetal hearing or growth either. 2
3. Gadolinium contrast is a separate question: first-trimester exposure runs roughly four to five times higher than exposure later in pregnancy, and while about 90 percent of a dose clears the body within a day, a small remaining trace can persist longer. 3
4. Research has tied gadolinium exposure at any point in pregnancy to a broader set of rheumatologic, inflammatory, or skin-related findings in children and to stillbirth or neonatal death, which is why it's used only when the benefit clearly outweighs that unknown risk. 1
5. Because an MRI itself involves no radioactive tracer, breastfeeding can continue right after the scan without any need to pause or set aside milk. 4

Is MRI scans safe in each trimester?

• First trimester. MRI used to be avoided in the first trimester out of caution, but current guidance no longer restricts non-contrast MRI to later pregnancy. A study of more than 1,700 first-trimester exposures found no increase in birth defects. Gadolinium contrast is different: exposure this early runs several times higher than in later trimesters, so it's reserved for when it's truly needed.
• Second trimester. Non-contrast MRI is standard practice in the second trimester when imaging is needed, with no effect on fetal growth or hearing found in the small studies that have looked. If your scan calls for contrast, your radiologist will weigh the lowest effective dose against what the images actually need to show.
• Third trimester. MRI stays the imaging option of choice over CT late in pregnancy too, since it avoids ionizing radiation. Gadolinium is still reserved for when its benefit clearly outweighs the unknown fetal risk, and your care team can talk through whether the same clinical question could be answered without it.