Patients' fertility can be affected both during cancer treatment--when an unplanned pregnancy could be a serious problem--and later, if the cancer treatment causes infertility. For patients who want to have children, this can be devastating.

First, it is important to know that you should prevent pregnancy during chemotherapy or radiation treatment and for at least six months after treatment. Although cancer treatment may lower a man's sperm count or cause a woman's menstrual period to stop, a pregnancy may still be possible. Talk to your doctor or nurse about the best method of birth control for you.

Chemotherapy drugs and radiation to the pelvis cause genetic changes in sperm and oocytes (eggs). Embryos with genetic damage often miscarry early in pregnancy. There is also a risk of having a baby with a birth defect, but so few babies have been conceived during a parent's cancer treatment that no statistics exist on the risk of birth defects.

If a woman is pregnant and her husband is having chemotherapy, using a condom will keep the medicines from reaching the fetus through intercourse. Also, during the first few days after having radioactive seed implants for prostate cancer, men may ejaculate a radioactive seed in their semen. The doctor can advise when it is safe to resume intercourse and whether to use a condom.

By six to 12 months after cancer treatment, the sperm that were exposed to chemotherapy or radiation have all been ejaculated. Eggs that are healthy enough to be ovulated are also more likely to be undamaged. In fact, both the eggs and the stem cells that produce sperm have some ability to repair genetic damage during the first several years after cancer treatment. However, genetic damage is common in human embryos even when neither parent has had cancer treatment. A third of very early pregnancies miscarry because the embryo had genetic damage, often without a woman's ever realizing she was pregnant.

If a woman already is pregnant at the time of cancer diagnosis, she may be able to continue the pregnancy and have a healthy baby even if she needs chemotherapy, particularly if the pregnancy is past the first three months, when most organs are formed. This situation occurs occasionally in young women with breast cancer.

The following pages provide information about fertility after cancer treatment:

Causes of Infertility

Preserving Fertility in Women

Preserving Fertility in Men

Recovery of Fertility After Cancer Treatment

Questions to Ask Your Doctor