Breast cancer and fertility

Fertility is known as the ability to get pregnant. If you’re a young woman diagnosed with breast cancer, treating the cancer might be the only thing on your mind — you may not necessarily be thinking about starting a family in those moments. But whether you’ve always known you’d like to start a family or you’re unsure, it’s important to know that some breast cancer treatments can make it harder to get pregnant.

Breast cancer treatments can impact fertility in different ways. For example:

• Chemotherapy can reduce the number of eggs in the ovaries.
• Hormonal therapy treatments such as tamoxifen or aromatase inhibitors, often given for 5 to 10 years, can interfere with the timing of starting a family. Taking hormonal therapy during pregnancy can harm the development of the fetus.
• If taken during pregnancy, targeted therapies can also harm the developing fetus.

Some fertility and pregnancy situations are unique and require specific kinds of care:

• If you’ve been diagnosed with metastatic breast cancer and are concerned about fertility through long-term treatment, visit our Fertility and metastatic breast cancer page to learn about protecting fertility and having children.
• If you are pregnant and recently diagnosed, visit Pregnant with breast cancer for information about safe treatment options and getting the support you need.

How some breast cancer treatments can impact fertility

Different breast cancer treatments can affect fertility in different ways. Here, we’ll talk about the ways that chemotherapy and hormonal therapy, two common treatments, can impact fertility.

Chemotherapy

Chemotherapy can affect fertility by damaging the DNA in immature egg cells in the ovaries. This means having fewer eggs than you did before chemotherapy.

Chemotherapy can also cause the ovaries to stop releasing eggs and making estrogen. This can trigger premature menopause, sometimes called medical menopause, in some women. After menopause, you can no longer get pregnant. But the younger you are, the lower the risk of chemotherapy-related menopause, especially if you’re under age 40.

Chemotherapy’s long-term effects on fertility depend on your dose and your age. Certain types of chemotherapy pose higher risks than others:

• Chemotherapies most likely to cause infertility include cyclophosphamide (Cytoxan).
• Cisplatin and doxorubicin (Adriamycin) likely pose a lower risk of causing infertility.
• Chemotherapies with a low risk of causing infertility include 5-fluorouracil (5-FU), gemcitabine (Gemzar), and methotrexate.

Some doctors advise not getting pregnant for at least 6 months after chemotherapy is finished. Others suggest waiting at least 2 years before trying to have a baby. The longer time frame increases the chances you have fully recovered from chemotherapy and also helps you and your care team make sure the cancer has not returned.

In a study published in 2019, researchers tested the effect of an ovarian suppression medicine called goserelin on fertility of women being treated for hormone receptor-negative breast cancer. The study showed that when women took the medicine with chemotherapy, their ovaries were protected from the effects of chemotherapy and they were more likely to have a baby after treatment. Research on this treatment combination, and its effects on fertility, is ongoing.

If you think you want to have children in the future, let your doctor know as early as possible before treatment starts. Ask to be referred to a fertility specialist to talk about options, such as freezing eggs or embryos for later use.

Hormonal therapy

Hormonal therapy can have an impact on your menstrual cycle and your fertility:

• It can cause irregular periods, or cause periods to stop, although you could still be fertile.
• It’s usually taken for 5 to 10 years, which can interfere with the timing of having a family.

It’s also important to know that hormonal therapy can harm an unborn baby, and cannot be taken while pregnant. That’s why your doctor may suggest using a long-acting non-hormonal reversible contraceptive (birth control) such as a copper IUD or barrier birth control such as a diaphragm or condoms while taking hormonal therapy.

Three types of hormonal therapy are approved for premenopausal women:

• Tamoxifen. Tamoxifen’s greatest effect on your fertility may come from the time delay caused by the recommended 5 to 10 years of treatment. Adding 5 to 10 years may push you into menopause, especially if you have also had chemotherapy. Even if you are not in menopause when you finish treatment, the older you are, the harder it is to become pregnant. Research suggests that taking tamoxifen for 2 or 3 years, pausing it to try to get pregnant, and then finishing the treatment after having a baby may be an option for some women. It’s important to know that it is possible to get pregnant while taking tamoxifen, but tamoxifen can harm a fetus. Doctors advise waiting at least 2 months after pausing or ending tamoxifen treatment before trying to become pregnant.
• Centrally acting hormone blockers, such as goserelin (Zoladex) and leuprolide (Lupron), are medicines that temporarily suppress ovarian function. These treatments lower estrogen levels so that estrogen receptor-positive breast cancer cells can’t continue to grow. When taken during chemotherapy, GnRH agonists can have a protective effect on fertility by telling the brain not to signal the ovaries to develop an egg that could potentially be harmed by chemotherapy.
• Aromatase inhibitors. While aromatase inhibitors, such as anastrozole (Arimidex), exemestane (Aromasin), and letrozole (Femara) used to be given only to postmenopausal women, they can now be given to premenopausal women in combination with medicines such as goserelin or leuprolide. Aromatase inhibitors in combination with ovarian suppression medicines have been shown to be more effective against estrogen receptor-positive breast cancer than tamoxifen. Aromatase inhibitors are usually given for 5 years.
  If hormonal therapy has been recommended for you and you want to have children, talk with your care team about your individual situation.

To learn more about timing hormonal therapy and starting a family, visit Getting pregnant after early breast cancer. You can also watch one woman’s video story about pausing tamoxifen to have a baby.

Ovarian shutdown or suppression

Ovarian suppression can be a side effect of centrally acting hormone blockers, such as goserelin and leuprolide, taken during chemotherapy. It can be temporary or permanent. This often depends on your age and how close you are to natural menopause. The younger you are, the more likely you are to become pregnant after treatment ends.

Ovarian shutdown can also be done on purpose for two different reasons:

• Temporary ovarian shutdown. Medicines such as goserelin or leuprolide can be used to temporarily stop the ovaries from producing estrogen and releasing eggs (ovulating). Ovarian suppression can:
  • Be combined with tamoxifen or other hormonal therapy to lower the amount of estrogen in the body and treat estrogen receptor-positive breast cancer
  • Protect the ovaries and future fertility from the effects of chemotherapy
• Permanent ovarian shutdown. Certain women at high risk for breast cancer or breast cancer recurrence may benefit from surgical removal of the ovaries (oophorectomy). Some people refer to this as medical menopause. This surgery causes permanent infertility.

Managing fertility

You may be able to get pregnant and have healthy babies after breast cancer treatment. If being able to have children is important to you, let your doctor know this before you start treatment, if possible. You may want to ask to be referred to a fertility specialist who has worked with women being treated for breast cancer. If you did not have a conversation about fertility and you’ve already started treatment, don’t worry. There are still options available. Talking with a fertility specialist can help.

Here are some questions to ask your oncologist and your fertility specialist:

• Does my prognosis affect my ability to have children?
• Is it safe for me to become pregnant after treatment? If so, when is the right time?
• What are my options for preserving fertility?
• Can I postpone treatment to have a baby?
• Are fertility drugs safe? Will I need to take them?
• How long does the fertility preservation process take for people who need to start treatment soon?

Learn more about protecting your fertility during treatment.

Pregnancy and wanting children

If you think you want to get pregnant after having breast cancer treatment, know that having a baby doesn’t make cancer more likely to recur or affect your long-term survival. Visit Getting pregnant after early breast cancer to learn more.

There are also other options for women who want to have a family after breast cancer treatment. Some women choose to use an egg donor or surrogate to help them have a baby. Others prefer to adopt.

Here are some organizations that provide financial assistance for fertility procedures, including surrogacy:

• BabyQuest Foundation
• Livestrong Fertility
• Heartbeat Fertility Preservation Program

For more detailed information about surrogate pregnancy, visit the American Pregnancy Association and the National Infertility Association.

To learn more about adopting a child, visit the National Council for Adoption.