What to Know About Breast Cancer and Pregnancy

Up until now, there’s no concrete evidence that breast cancer affects your baby from developing properly in the womb. You cannot pass cancer on to your baby, and there isn't any evidence that your baby will develop cancer because you had breast cancer while you were pregnant. However, that doesn't stop it from being a primary health concern.

Midsection of pregnant Black woman holding belly

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Breast Cancer and Fertility

Three things can potentially affect fertility in people who have breast cancer: the type of cancer treatment used, the type and stage of your cancer when it is diagnosed, and your age.

Type of Cancer Treatment Used

Different methods are used to treat cancer. However, not all of them affect fertility. Radiation and hormonal therapy affect fertility to a lesser degree, while chemotherapy can damage the ovaries and have a bigger impact on your fertility.

Chemotherapy works by killing cells in the body that are dividing quickly. The hormones, such as estrogen, needed to release eggs each month and prepare the uterus for a possible pregnancy are made in the cells of the ovaries called oocytes. Oocytes tend to divide quickly, so are often affected by chemotherapy.

Chemotherapy can therefore lead to loss of those important hormones and affect fertility. Sometimes a woman undergoing chemotherapy treatment will go into early menopause.

Chemo drugs that are linked to the risk of infertility in females are:

  • Carboplatin
  • Cyclophosphamide
  • Doxorubicin

Higher doses of these drugs are more likely to cause permanent fertility changes, and combinations of drugs can have greater effects.

Stage and Type of Cancer

Being diagnosed with cancer doesn’t necessarily mean that you need chemotherapy. It all depends on the type of cancer and the stage it’s in when you’re diagnosed. 

If your cancer is more advanced, chemotherapy will most likely be recommended, which may affect your ovaries and therefore fertility. Minor tumors with small nodes that are not as likely to spread are treated differently.

Some breast cancers are treated with hormonal drugs. According to the American Cancer Society, two out of every three breast cancer cases are hormone-sensitive. However, for cases that aren’t, you’ll have no other choice but to accept chemotherapy.  

Patient’s Age

The younger you are, the more eggs you usually have in your ovaries. This gives you a higher chance to preserve some fertility despite damage caused by treatments like chemotherapy. Women who are treated for cancer before they turn 35 have the best chance of becoming pregnant after treatment. 

Is Breast Cancer Hereditary?

Studies have shown that less than 15% of people who have close relatives with breast cancer are at risk of getting breast cancer. Also, 5% to 10% of breast cancers are linked to gene mutations that are inherited from one's parents. This shows that a small number of cases can be inherited, but it's not common.

Breast Cancer and Gestation

One study examined children who were exposed to chemotherapy in the uterus, and they didn't have cancer.

If you are diagnosed with breast cancer while you are pregnant, some treatment options will have to be postponed until after delivery. This is to avoid complications like miscarriage or anything that will affect full-term delivery.

The kind of treatment your doctor will recommend for you will depend greatly on the stage of your cancer. Your doctor will consider:

  • The rate of the cancer cell growth
  • The number and size of tumors
  • The exact type of breast cancer
  • Your overall wellness
  • The duration of your pregnancy

Breast Cancer Doctor Discussion Guide

doctor discussion guide


The most common treatment option for breast cancer is surgery. There are two kinds: lumpectomy and mastectomy (breast tissue removal). 

Some experts say that breast surgery at the early stage of breast cancer is fine, but general anesthesia may pose some risk to your baby.


Research has shown that it’s safe to use chemotherapy during therapy from the second trimester. This is why your doctor may most likely not advise chemotherapy during your first trimester of pregnancy.

However, chemo drugs aren’t administered in the last three weeks of pregnancy. In some cases, waiting until you deliver is the best option. 


Your oncologist may discourage radiation therapy since high doses of radiation at any point of your pregnancy can potentially harm your baby.

The risks associated with radiation therapy during pregnancy include:

  • Cancer, especially during childhood
  • Slow fetal growth
  • Birth abnormalities
  • Miscarriage

Hormone and Targeted Therapies

Hormone therapies and targeted therapies like aromatase inhibitors aren’t advised for use during pregnancy. Some hormone therapy drugs, such as tamoxifen, can cause birth defects.

Targeted therapy drugs attack cancer cells differently from standard chemo drugs. Little is known about their effects on fertility or problems during pregnancy. However, what's known is that some targeted drugs (thalidomide and lenalidomide) have such a high danger of causing birth defects that women are asked to use two effective types of birth control while taking them.

Other therapies you should avoid are:

  • Palbociclib
  • Tamoxifen
  • Trastuzumab
  • Bevacizumab
  • Everolimus
  • Lapatinib

Breast Cancer and Postpartum

You may experience some challenges while breastfeeding your child after surgery or radiation therapy.

One study showed a reduction in milk production in people who had breast cancer. These structural changes increased sensitivity in the breast and made it difficult for the baby to breastfeed. Nevertheless, a sizable amount of women in the study were able to breastfeed.

If you underwent hormone therapy and were placed on medications, consult your doctor before trying to breastfeed. Some drugs can be passed on to your baby through the breast milk when they breastfeed and affect them.


Some forms of breast cancer treatment like chemotherapy can potentially affect your ability to conceive and have a healthy baby. Other treatments like hormonal therapy may not affect your fertility, but they can lead to birth defects. If you have breast cancer and are pregnant or want to get pregnant, talk to your doctor about your treatment plan and how you can increase your chances of not only conceiving but also having a healthy baby.

Frequently Asked Questions

How do you diagnose breast cancer in a pregnant person?

Signs like tender breasts and swelling make it quite challenging to diagnose breast cancer in pregnant people. You may need to check for other signs like dimpling of the skin, bloody discharge from the nipple, scaly breast skin, or any uncommon thickening in any part of the breast.  

How do pregnancy and HRT influence breast cancer risk?

Hormone replacement therapy (HRT) increases estrogen levels, and higher levels of estrogen can stimulate cell growth. This may help breast cancer cells grow, resulting in a higher breast cancer risk. Similarly, women are exposed to higher levels of hormones like estrogen and progesterone during pregnancy, which increases their breast cancer risk.

How does pregnancy and lactation change breast tissue?

During pregnancy and lactation, your breast tissue continues to grow and your milk-producing cells get bigger. Sometimes you may experience pain due to these developments in your breast. Your body will also experience a rise in estrogen, progesterone, and prolactin, which increase the water, electrolyte, and fat content in your breast tissues.

How can breast cancer treatment affect someone who wants to get pregnant?

Chemotherapy and drugs like cyclophosphamide can negatively affect the ovaries and fertility. Other therapies like radiotherapy and hormonal therapy do not affect your fertility as much as chemotherapy does.

A Word From Verywell

Discovering that you have breast cancer especially during pregnancy, or coping with breast cancer while pregnant, can be devastating and stressful for you and your family. Treatment like chemotherapy can potentially harm both your chances of getting pregnant and your baby.

Consult your doctor to discuss the treatments you’ll need and what changes you need to make to your treatment plan. With the right interventions, you can still get pregnant and give birth to a healthy baby.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. American Cancer Society. How cancer treatment can affect fertility in females.

  3. American Cancer Society. Hormone therapy for breast cancer.

  4. Breastcancer.org. Breast cancer statistics.

  5. Keyser EA, Staat BC, Fausett MB, Shields AD. Pregnancy-associated breast cancer. Rev Obstet Gynecol. 2012;5(2):94-99.

  6. Keyser EA, Staat BC, Fausett MB, Shields AD. Pregnancy-associated breast cancer. Rev Obstet Gynecol. 2012;5(2):94-9.

  7. Treating breast cancer during pregnancy.

  8. Cohen JM, Hutcheon JA, Julien SG, Tremblay ML, Fuhrer R. Insufficient milk supply and breast cancer risk: a systematic review. PLoS One. 2009 Dec 14;4(12):e8237. doi:10.1371/journal.pone.0008237

  9. National Cancer Institute. Reproductive history and cancer risk.

Additional Reading

By Margaret Etudo
Margaret Etudo is a health writing expert with extensive experience in simplifying complex health-based information for the public on topics, like respiratory health, mental health and sexual health.