Female Fertility and Cancer Treatment

Author: Christina Bach, MBE, LCSW, OSW-C
Last Reviewed: November 27, 2023

The article may be useful for people born with ovaries and a uterus.

Fertility is the ability to become pregnant and have a child. When a female is born, her ovaries hold hundreds of thousands of eggs. Starting at the end of puberty until menopause, about 15-20 immature eggs (oocytes) are released every month. One of these will fully develop and become a mature oocyte. This mature oocyte is released into the fallopian tube. The egg is then either fertilized by sperm, which leads to pregnancy, or a woman will get her period (menstruate).

Over a lifetime, about 400-500 mature oocytes are released into the fallopian tubes. The undeveloped oocytes or the follicles needed to develop them can be damaged by cancer treatment. This can cause your period to change or stop. This can lead to infertility (being unable to get pregnant). Damage to the uterus or cervix by radiation or surgery can affect your ability to carry a pregnancy to term.

Chemotherapy and Fertility

Chemotherapy works by killing quickly dividing cells. Many cells in our bodies divide quickly, like those lining the gut, hair follicles, and germ cells (including sperm and oocytes/eggs). Both cancerous and non-cancerous cells can be affected by chemotherapy. When these cells are damaged by chemotherapy, it causes side effects. These include diarrhea, mouth sores, hair loss, and being unable to have children (infertility).

There is no way of knowing which women treated for cancer will become infertile. The risk is based on

  • The medication(s) used: receiving more than one medication makes predicting fertility even harder. the dose that is given.
  • How long it is given for and what doses are given: higher doses and longer treatments increase the risk of fertility.
  • Your age at the time you had chemotherapy: The older you are at the time of the treatment, the more likely it is that your periods will stop and/or you will become infertile.
  • The size of the follicle pool (or the number of oocytes) before chemotherapy. Since this number lowers with age, the older you are, the higher your risk of infertility becomes because there are fewer oocytes to begin with.

Many studies look at when the menstrual cycle restarts as a predictor of fertility. Pregnancy cannot happen if your period doesn't return. However, the return of periods does not always mean you can get pregnant. Women who get their period back after therapy are still at risk of starting menopause earlier than women who did not have chemotherapy or radiation.

With all of this in mind, we know that the group of chemotherapy agents called alkylating agents poses the greatest risk of causing infertility. These include:

Bevacizumab, a type of targeted therapy, has been found to cause ovarian failure that is sometimes permanent. Little is known about other targeted therapies. Thalidomide and lenalidomide are examples of medications that can cause birth defects, so you will be asked to use two forms of birth control while on these. Ask your provider about the possible risks for birth defects related to the medications you are receiving.

Treatments used to prepare for stem cell and bone marrow transplants are likely to cause infertility in women. Transplant regimens using busulfan and/or cyclophosphamide are more toxic to a woman's fertility than those using melphalan. Studies have found that girls treated for childhood cancers before puberty have a good chance of regaining ovarian function.

There is not enough research on newer medications to know how they will affect fertility. If you are getting or have received chemotherapy, it is important to speak to your provider about when it is safe for you to try to become pregnant. Each therapy can affect you differently, so it is important to talk openly with your team about your plans for having children in the future.

Radiation Therapy and Fertility

The effect of radiation therapy on fertility depends on

  • The dose received.
  • The part of the body treated.
  • Your age at the time of treatment: As with chemotherapy, the size of the follicle pool before treatment is linked to the number of oocytes remaining after therapy. Younger women are more likely to have a larger pool and are less likely to enter permanent menopause at the time of therapy.

Younger women who regain periods (menses) after radiation therapy are at risk of starting menopause earlier than women who did not have radiation or chemotherapy. Predicting when this menopause will happen is hard, putting pressure on younger women who wish to have a natural pregnancy. As with chemotherapy, women who start to have their periods after treatment are not always able to get pregnant.

Total body irradiation (TBI) is a technique used for stem cell and bone marrow transplants in which the whole body is irradiated. This treatment has been found to have a great effect on fertility in women, leading to permanent ovarian failure in many of these patients. Girls who have received TBI before puberty are more likely to get back ovarian function than those who received it after puberty.

Radiation therapy to the belly or pelvis can cause harm to the uterus and/or cervix. This can make it hard to carry a pregnancy to term. Studies have found that radiation can cause changes to the muscles, blood flow, and size of the uterus. This may keep an embryo from implanting. If you have received radiation to the uterus, you are at higher risk for miscarriage, preterm labor, and low birth weight babies. Despite these risks, the risk of birth defects is not increased, so long as radiation is not given during pregnancy.

The pituitary gland, found in the brain, makes hormones (LH and FSH) that stimulate the ovary to make and release a mature female oocyte. Radiation therapy to the brain can harm the pituitary gland, affecting the ovulation cycle. This can lead to a shorter time for fertilization after ovulation. This can often be fixed by taking supplemental hormones.

Surgery and Fertility

Surgery that removes both ovaries or the uterus, cervix, and/or fallopian tubes will affect fertility. Depending on how advanced the cancer is, you may be eligible for fertility-preserving surgeries and should discuss these choices with your surgeon.

Hormone Therapy

Tamoxifen can temporarily stop or change menstruation, but this does not happen in all women. It is possible to become pregnant while on tamoxifen, so you should use two forms of birth control to prevent pregnancy. If you become pregnant while on tamoxifen, the medicine should be stopped right away due to the risk to the fetus. Also, tamoxifen can affect estradiol and FSH levels, making it hard to test ovarian function in women on the medicine (see assessment of ovarian function below).

Assessment of Ovarian Function after Therapy

The return of a woman’s period is not a good predictor of fertility. There are a few tests that can help check fertility. Follicle-stimulating hormone (FSH) and estradiol (E 2) are hormone levels, which can be checked by a blood test on the 3rd day of menstruation. These levels are used to assess ovarian follicle reserve (number of eggs remaining in the ovary) and fertility.

These levels cannot predict exactly how many follicles are left or how long before infertility will start. One hormone, anti-Mullerian hormone (AMH), is made by early follicles and is a good predictor of the follicle reserve. Using ultrasound to count the number of antral follicles (those oocytes that are growing) on the 3rd day of the menstrual cycle can also be a good marker of follicle reserve. The number of follicles maturing is linked to the number that remains. While tamoxifen affects the levels of FSH and E 2, it does not affect the antral follicle count, so this test may be useful in predicting future fertility in women taking tamoxifen.

If I still ovulate, is there any danger or risk of becoming pregnant after therapy?

There is concern about possible birth defects caused by exposure of oocytes to cancer therapies. Studies have found no increase in birth defects in the children of cancer survivors, nor do these children have higher rates of cancer themselves (this does not apply to families with genetic cancer syndromes).

The DNA of oocytes can be harmed by cancer therapies, but this damage can repair itself in the months after treatment (the exact time needed for repair is unknown). Your team may suggest that you wait a certain amount of time after treatment before trying to get pregnant. It is important to discuss your case with your oncology team. You may also want to talk with a fertility expert who works with cancer patients.

For breast cancer survivors, there has always been concern that pregnancy after treatment could increase the risk of recurrence, especially in estrogen receptor-positive tumors. However, studies have found that pregnancy does not appear to increase the risk of recurrence. Studies have not tested if it is safe for breast cancer survivors to take fertility medications if they are not able to get pregnant naturally.

You can also learn more about fertility preservation options and find links to resources for more information.


American Cancer Society. How Cancer Treatment Can Affect Fertility in Women. 2017. Found at: https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/fertility-and-sexual-side-effects/fertility-and-women-with-cancer/how-cancer-treatments-affect-fertility.html

Devita Jr, V. T., Lawrence, T. S., & Rosenberg, S. A. (2015). DeVita, Hellman, and Rosenberg's cancer: principles & practice of oncology. Lippincott Williams & Wilkins.

Lee SJ, Schover LR, Partridge AH, et al: American Society of Clinical Oncology recommendations on fertility preservation in cancer patients. Journal of Clinical Oncology 24:2917-31, 2006.

Leitao, MM & DS Chi: Fertility-sparing options for patients with gynecologic malignancies. The Oncologist 10:613-622, 2005.

Nieman CL, Kazer R, Brannigan RE, et al: Cancer survivors and infertility: a review of a new problem and novel answers. Journal of Supportive Oncology 4:171-8, 2006.

Oktay, K., Harvey, B. E., Partridge, A. H., Quinn, G. P., Reinecke, J., Taylor, H. S., ... & Loren, A. W. (2018). Fertility preservation in patients with cancer: ASCO clinical practice guideline update. Journal of Clinical Oncology, JCO-2018.

Poorvu, P. D., Frazier, A. L., Feraco, A. M., Manley, P. E., Ginsburg, E. S., Laufer, M. R., ... & Partridge, A. H. (2019). Cancer treatment-related infertility: a critical review of the evidence. JNCI Cancer Spectrum, 3(1), pkz008.

Save My Fertility. Found at: https://www.savemyfertility.org/

Schover L. State-of-the-art: parenthood after chemotherapy. Program and abstracts of the American Urological Association 2006 Annual Meeting; May 20-25, 2006 ; Atlanta, Georgia. Plenary Session II.

Simon B, Lee SJ, Partridge AH, et al: Preserving fertility after cancer. CA: A Cancer Journal for Clinicians 55:211-28; quiz 263-4, 2005.

The Oncofertility Consortium. Found at: http://oncofertility.northwestern.edu/for-patients

Thomson, AB, Critchley, H, Kelnar, CJ and WHB Wallace: Late reproductive sequelae following treatment of childhood cancer and options for fertility preservation. Best Practice & Research Clinical Endocrinology & Metabolism, 16(2) 311-334, 2002.

Wallace, WH & TW Kelsey: Ovarian reserve and reproductive age may be determined from measurement of ovarian volume by transvaginal sonography. Human Reproduction 19:1612-1617, 2004


December 20, 2023

Surprise! Financial Assistance To Help With Your Medical Bills May Be Available!

by Christina Bach, MSW, LCSW, OSW-C

October 12, 2023

3…2…1…Countdown to Medicare Open Enrollment

by Christina Bach, MSW, LCSW, OSW-C

October 11, 2023

3…2…1…Countdown to Medicare Open Enrollment

by Christina Bach, MSW, LCSW, OSW-C