Finding Breast Cancer During Pregnancy

Breast cancer during pregnancy is rare. But if you find a lump or notice any changes in your breasts that concern you, tell your doctor or nurse right away. There are a variety of tests a pregnant woman may have if breast cancer is suspected. There are options for treating breast cancer if you are pregnant.

If you are pregnant and breast cancer is found, it may be called gestational breast cancer or pregnancy-associated breast cancer (PABC)

How common is breast cancer during pregnancy?

Breast cancer is found in about 1 in every 3,000 pregnant women. Having breast cancer during pregnancy is very rare. But breast cancer is the most common type of cancer found during pregnancy, while breastfeeding, or within the first year of delivery.  

Breast cancers can be harder to find when you’re pregnant

Hormone changes during pregnancy cause the breasts to change. They may become larger, lumpy, and/or tender. This can make it harder for you or your doctor to notice a lump caused by cancer until it gets quite large.

Another reason it may be hard to find breast cancers early during pregnancy is that many women put off breast cancer screening with mammograms until after the pregnancy. And because pregnancy and breastfeeding can make breast tissue denser, it can be harder to see an early cancer on a mammogram.

Because of these challenges, when a pregnant woman develops breast cancer, it’s often diagnosed at a later stage than it would be if she were not pregnant. It’s also more likely to have spread to the lymph nodes.

What to look for

If you find a lump or notice any changes in your breasts that concern you, don’t ignore it. Tell your doctor or nurse right away. If your doctor doesn’t want to check it out with a mammogram, ask about other kinds of imaging tests such as ultrasound or MRI. You may need to get a second opinion. Any suspicious breast changes should be checked out or even biopsied (see below) before assuming they are a normal response to pregnancy.

Are mammograms safe during pregnancy?

Mammograms can find most breast cancers that start when a woman is pregnant, and it’s thought to be fairly safe to have a mammogram during pregnancy. The amount of radiation needed for a mammogram is small. And the radiation is focused on the breasts, so that most of it doesn’t reach other parts of the body. For extra protection, a lead shield is placed over the lower part of the belly to help keep radiation from reaching the womb. Still, scientists can’t be certain about the effects of even a very small dose of radiation on an unborn baby.

Even during pregnancy, early detection is an important part of breast health. Talk to your doctor or nurse about the best time for your next mammogram.

Breast biopsy during pregnancy

A new lump or abnormal imaging test result may cause concern, but a biopsy is the only way to find out if a breast change is cancer. During a biopsy a small piece of tissue is taken from the area of concern. Breast biopsies are most often done using a needle. They’re usually done as an outpatient procedure, even if you’re pregnant. The doctor uses medicine to numb just the area of the breast involved in the biopsy. This causes little risk to the fetus.

If a needle biopsy doesn’t give an answer, a surgical biopsy is the next step. This means taking out a piece of tissue through a small cut (incision) in the breast. Surgical biopsies are often done under general anesthesia (where drugs are used to put the patient into a deep sleep), which carries a small risk to the fetus.

Tests to stage the breast cancer

If breast cancer is found, you’ll need other tests to find out if cancer cells have spread within the breast or to other parts of the body. This process is called staging. Different staging tests may be needed, depending on your case.

Tests like ultrasound and magnetic resonance imaging (MRI) scans do not use radiation and are thought to be safe during pregnancy. But the contrast material (dye) sometimes used in MRI crosses the placenta, the organ that connects the mother to the fetus. This dye has been linked with fetal abnormalities in lab animals. For this reason, an MRI with contrast dye is not recommended during pregnancy. An MRI without contrast can be used if needed.

Chest x-rays are sometimes needed to help make treatment decisions. They use a small amount of radiation. They’re thought to be safe to have when you’re pregnant, as long as your belly is shielded.

Other tests, such as PET scans, bone scans, and computed tomography (CT) scans are more likely to expose the fetus to radiation. These tests are not often needed, especially if the cancer is thought to be just in the breast. If one of these tests is needed, doctors might be able to make adjustments to limit the amount of radiation exposure to the fetus. Treatments are available if a pregnant woman has breast cancer. Learn about treating breast cancer during pregnancy.

Can breast cancer spread to the baby?

In very few cases, the cancer has reached the placenta (the organ that connects the mother to the fetus). This could affect the amount of nutrition the fetus gets from the mother. But there are no reported cases of breast cancer being transferred from the mother to the fetus.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Burstein HJ, Harris JR, Morrow M. Malignant Tumors of the Breast. In DeVita VT Jr, Lawrence TS, Rosenberg SA, eds. Cancer: Principles and Practice of Oncology 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2011: 1437-1438.

Grigg A. Special Issues in Pregnancy, Specific Malignancies: Breast Cancer. In: Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG, eds. Clinical Oncology. 4th ed. Philadelphia, PA: Elsevier Inc.; 2008:1054-1055.

National Cancer Institute. Breast Cancer Treatment and Pregnancy (PDQ®). Accessed at www.cancer.gov/cancertopics/pdq/treatment/breast-cancer-and-pregnancy/healthprofessional/allpages on September 30, 2013.

Taylor D, Lazberger J, Ives A, Wylie E, Saunders C. Reducing delay in the diagnosis of pregnancy-associated breast cancer: how imaging can help us. J Med Imaging Radiat Oncol. 2011 Feb;55(1):33-42.

Viswanathan S, Ramaswamy B. Pregnancy-associated Breast Cancer. Clin Obstet Gynecol. 2011;54(4):546-555.

Yang WT, Dryden MJ, Gwyn K, et al. Imaging of breast cancer diagnosed and treated with chemotherapy during pregnancy. Radiology. 2006;239(1):52-60.

Last Medical Review: June 1, 2016 Last Revised: August 18, 2016

American Cancer Society medical information is copyrighted material. For reprint requests, please contact permissionrequest@cancer.org.