Do I need to tell the technologist I am pregnant?

Yes. Tell the scheduler and the technologist before the exam, even if you are only a few weeks along. It does not usually stop the mammogram, but it helps the team choose the right test and decide on extra steps such as an abdominal shield.

Does it matter which trimester I am in?

Not for a mammogram. The dose that reaches the uterus is so small that it stays far below the levels the CDC links to any fetal effect at every stage of pregnancy. The breast does get denser as pregnancy goes on, which can make the pictures harder to read later in pregnancy.

Can I get a 3D mammogram while pregnant?

Yes. The 2025 ACR criteria rate screening tomosynthesis (3D mammography) as usually appropriate for pregnant women 40 and older, the same as standard mammography. The panel notes 3D imaging may help in the denser breast tissue of pregnancy.

Is a breast biopsy safe while pregnant?

Yes. The ACR panel says core needle biopsies can be safely performed during pregnancy. Bleeding risk is higher because the breast has more blood flow, and there is a small risk of a milk fistula that rises closer to delivery.

What if I had a mammogram before I knew I was pregnant?

This is a common worry, and the numbers are reassuring. Scatter to the uterus from a standard mammogram is negligible, and the CDC says noncancer effects are not detectable below a fetal dose of about 0.10 Gy. Tell your obstetrician so it is in your record, but it is not a reason for alarm.

Can You Get a Mammogram While Pregnant?

The short answer: Yes. The American College of Radiology (ACR) states that mammography is safe during pregnancy, and the radiation that reaches the uterus is negligible. A new lump is usually checked with ultrasound first, with a mammogram added for women 30 and older or when the ultrasound looks suspicious. Tell the staff you are pregnant, but do not let pregnancy delay a breast problem.

Is a mammogram safe during pregnancy?

Yes. The 2025 ACR Appropriateness Criteria on Breast Imaging During Pregnancy say plainly: "Mammography is safe to perform during pregnancy." The expert panel, which included a representative of the American College of Obstetricians and Gynecologists (ACOG), repeats in its full narrative that "scatter radiation to the fetus is negligible."

The reason is simple geometry. The x-ray beam is aimed through a compressed breast and into a detector plate. It does not point at the abdomen. Only a tiny amount of scattered radiation travels down the body toward the uterus.

That does not mean every pregnant woman needs a mammogram. It means that when one is the right test, pregnancy is not a reason to skip it.

Should you keep up routine screening while pregnant?

For many women, yes. This is where the 2025 ACR guidance is more direct than older advice. Its abstract states that "both high- and normal-risk women should continue their routine screening mammography examinations during pregnancy." The panel splits screening into three groups:

Age 40 or older, any risk: screening mammography and screening 3D mammography (tomosynthesis) are rated "usually appropriate."
Age 25 or older with higher-than-average risk: screening mammography and 3D mammography are also "usually appropriate." The panel adds that the benefits need to be weighed against the risks for each patient.
Under 25 with higher-than-average risk: screening mammography is "usually not appropriate." Breast ultrasound "may be appropriate" instead.

Screening MRI is a different story, which we cover below. Practices still vary on routine screening for women with no symptoms. If you are due for your yearly exam, raise it with your obstetrician and the imaging center. Our guide to screening versus diagnostic mammograms explains how the two exams differ.

What test comes first if you find a lump?

Ultrasound. It uses sound waves, not radiation, and it sees through dense pregnant breast tissue well. The ACR panel rates breast ultrasound as "usually appropriate" for focal pain or a lump in pregnant women of any age. What comes next depends on your age:

Under 30: ultrasound alone is the first test. The panel rates diagnostic mammography and 3D mammography as "usually not appropriate" as the first step. They become useful add-ons if the ultrasound looks suspicious.
30 or older: diagnostic mammography or 3D mammography is also "usually appropriate" alongside ultrasound. For women 40 and older, the panel says mammography should be part of the first workup.

The ACR says a dominant lump that lasts 2 weeks or more should be evaluated. It also notes that most lumps in pregnancy are benign. More than 80% of biopsied lumps in pregnancy turn out not to be cancer. Common causes include fibroadenomas, cysts, and normal tissue changes.

A 2023 review in RadioGraphics describes the same order. Ultrasound comes first, "followed by mammography if the US findings are suspicious for malignancy or do not show the cause of the clinical symptom." The National Cancer Institute agrees that the first test for a suspicious mass "is typically an ultrasound."

How much radiation reaches the baby?

Almost none. A 2008 study in Radiology modeled where the radiation goes during a standard four-view mammogram. The highest dose to the uterus or a first-trimester fetus was less than 0.001% of the dose absorbed by the breast. The authors concluded that "the dose to the first-trimester fetus is minimal."

Now compare that with the levels that matter. The CDC guidance for clinicians states that noncancer effects "are not detectable for fetal doses below about 0.10 Gy" (100 milligray). A 2021 review in Radiation Protection Dosimetry says fetal effects such as reduced IQ "are not expected to occur at an absorbed dose under 100 mGy." Because the uterus receives less than 0.001% of what the breast absorbs, the fetal dose from a mammogram sits far below that line.

Some centers also wrap a lead apron around the abdomen. The same 2021 review says this cuts the "already very low doses to the uterus" by about half. The NCI lists a lead shield as one way staff may limit exposure. Our post on how much radiation a mammogram exposes you to puts the breast dose itself in context.

What do ACOG and the ACR say about other breast tests?

ACOG's Committee Opinion 723, reaffirmed in 2026, sets the general rule. Ultrasound and MRI "are the imaging techniques of choice for the pregnant patient." X-ray exams deliver a dose "much lower than the exposure associated with fetal harm." If an x-ray test is needed, it "should not be withheld from a pregnant patient."

Breast MRI is the exception. A breast MRI needs gadolinium contrast to find cancer. The ACR panel notes that gadolinium crosses the placenta and its safety for the fetus is unknown. ACOG treats it as a relative contraindication. Radiology societies treat it as a contraindication in pregnancy. The ACR rates contrast breast MRI "usually not appropriate" in every pregnancy scenario, and finds no evidence for MRI without contrast either. The ACR also rates these as usually not appropriate:

Contrast-enhanced mammography: iodinated contrast crosses the placenta, and there are no data on fetal harm.
Molecular breast imaging (sestamibi): the tracer crosses the placenta and exposes the fetus to radiation for no benefit.

MRI of other body parts without contrast is a separate question. mri.md covers it in can you get an MRI while pregnant.

Why should a breast change not wait until after delivery?

Breast cancer during pregnancy is rare, but it is often found late. The NCI says it occurs in about 1 out of every 3,000 pregnancies, most often in women aged 32 to 38. The ACR panel notes that it is becoming more common as more women have children later in life.

Pregnancy makes it harder to find. The breasts grow larger and denser, which hides small lumps on exam and on a mammogram. The ACR says this can delay diagnosis. Pregnancy-associated cancers are often larger and more advanced, with lymph node involvement at the time they are found. The 2023 RadioGraphics review puts it plainly: imaging "should not be deferred, because delayed diagnosis of pregnancy-associated breast cancer contributes to poor outcomes."

Signs to report to your obstetrician include:

A lump that does not go away after about 2 weeks
Bloody discharge from a single duct
Skin thickening, or redness that does not improve with antibiotics
Sudden, diffuse swelling of one breast

If a biopsy is needed, it can be done. The ACR says core needle biopsies "can be safely performed during pregnancy," with a higher bleeding risk and a small risk of a milk fistula. After the baby arrives, the rules change again. Our guide to getting a mammogram while breastfeeding covers that stage.

The bottom line

You can have a mammogram while pregnant. The ACR calls it safe, and the dose to the uterus is less than 0.001% of the breast dose. That is far below the 100 milligray level linked to fetal effects. For a new lump, ultrasound comes first, with a mammogram added at age 30 or older or when the ultrasound is suspicious. The 2025 ACR criteria support routine screening for pregnant women 40 and older and for higher-risk women 25 and older. Contrast breast MRI is the test to avoid. Most lumps in pregnancy are benign, but any lasting change deserves a prompt look.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your obstetrician and your imaging center about any breast change during pregnancy, and tell the technologist you are pregnant before any x-ray exam.