Is MRI Safe During Pregnancy?

Is MRI Safe During Pregnancy?

Short answer: Yes. MRI does not use ionizing radiation, and the American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG) consider it safe in any trimester when the exam is medically indicated. The main precaution is contrast: gadolinium is generally avoided in pregnancy unless the benefit clearly outweighs the risk, and most pregnancy MRIs are performed without it.

If your doctor has recommended an MRI while you are pregnant, it is normal to worry. The good news is that MRI is the imaging test physicians prefer when a pregnant patient needs detailed pictures that ultrasound cannot provide. Here is what the evidence says and what to expect at Advanced Medical Imaging in Seminole, FL.

Why MRI Is Different From CT and X-Ray

X-ray and CT create images with ionizing radiation. MRI does not. It uses a strong magnetic field and radio waves to map the water in your tissues — the same physics whether you are pregnant or not. There is no dose to add up and no fetal radiation exposure to calculate.

That is why, when a pregnant patient has symptoms that ultrasound cannot fully explain — severe headache, suspected appendicitis, back pain with neurological signs, a pelvic mass — MRI is usually the next test rather than CT.

What the Research Shows

The largest study on this question followed more than 1.4 million births in Ontario, Canada, and was published in JAMA in 2016. Children exposed to non-contrast MRI in the first trimester had no increased risk of stillbirth, neonatal death, congenital anomalies, hearing loss, or vision loss compared with unexposed children.

ACOG Committee Opinion 723 (Guidelines for Diagnostic Imaging During Pregnancy and Lactation) states that MRI is not associated with fetal risk and should not be withheld from a pregnant patient when it is indicated. The ACR Manual on MR Safety reaches the same conclusion and does not require special consent for non-contrast MRI in pregnancy.

Trimester by Trimester

• First trimester (weeks 1–13): No documented harm from non-contrast MRI. Because this is the period of organ formation, some radiologists prefer ultrasound first when it can answer the question — but MRI is performed when needed and has not been shown to cause birth defects.
• Second trimester (weeks 14–27): Often the preferred window for elective or non-urgent MRI, including fetal MRI ordered by maternal-fetal medicine specialists.
• Third trimester (weeks 28–40): Safe. The practical challenge is comfort — lying flat can be difficult late in pregnancy. Tell us in advance so we can position you on your side or choose our Open MRI if that is easier.

What About Contrast (Gadolinium)?

This is the one real caution. Gadolinium-based contrast crosses the placenta and enters the amniotic fluid, where it can remain for an extended period. The same Ontario study found that gadolinium exposure in pregnancy was associated with a small increase in stillbirth/neonatal death and in certain inflammatory and skin conditions in childhood.

For that reason:

• Non-contrast MRI is the default in pregnancy.
• Gadolinium is used only when it will change management and no alternative exists — a decision made jointly by your OB, referring physician, and radiologist.
• If you have already had gadolinium before you knew you were pregnant, a single exposure is not considered a reason for alarm; discuss it with your OB.

Read more about how contrast works in our gadolinium contrast guide.

Common Concerns, Answered

Does the magnet heat the baby? MRI radiofrequency energy causes a tiny amount of tissue warming. Scanners are limited to safe levels (the "normal operating mode"), and studies have not found fetal harm at diagnostic settings.

Is the noise harmful? MRI is loud, but the fluid and tissue around the fetus dampen the sound substantially. The 2016 study found no increase in hearing loss. You will still wear ear protection.

Can I have an MRI if I am breastfeeding? Yes. Even after gadolinium, ACR and ACOG state you do not need to interrupt breastfeeding — less than 0.04% of the dose reaches breast milk, and almost none of that is absorbed by the infant.

Does AMI require a pregnancy test before MRI? No. We ask every patient about pregnancy at screening so the radiologist can tailor the protocol, but a known or suspected pregnancy does not prevent a non-contrast MRI.

When CT or X-Ray Is Still the Right Call

MRI is not always available fast enough for a true emergency, and some conditions (a suspected pulmonary embolism, significant trauma) are evaluated with CT even in pregnancy because the fetal dose from a single well-shielded exam is far below the threshold associated with harm. Your emergency physician weighs that in real time. For a deeper look at those numbers, see our post on radiation safety and risk.

What to Tell Us When You Schedule

1. That you are pregnant (or may be), and how many weeks along.
2. Whether your doctor ordered contrast — we will confirm the plan with the radiologist.
3. Any comfort needs — positioning, claustrophobia, or a preference for our open-bore scanner.

Pregnant self-pay patients do not need an outside referral for MRI at AMI; our physician reviews the request the same day. Learn more about MRI without a referral or see self-pay MRI pricing.

Schedule Your MRI

Radiation-free imaging, board-certified radiologists, and a team that scans expectant patients regularly. Schedule online or call (727) 398-5999 and let us know you are pregnant — we will take it from there.

Sources: - Ray JG et al. Association Between MRI Exposure During Pregnancy and Fetal and Childhood Outcomes. JAMA. 2016 - ACOG Committee Opinion No. 723 — Guidelines for Diagnostic Imaging During Pregnancy and Lactation - ACR Manual on MR Safety