Will chemotherapy make me infertile?

It might, but not always, and the effect is often not permanent. Whether chemotherapy affects fertility depends mainly on three things: the type of medicines used, the total amount received over the whole course, and your age at the time of treatment. Some medicine groups, particularly alkylating medicines such as cyclophosphamide, and high-dose treatment before a stem cell transplant, are more likely to cause lasting damage to the ovaries or to the cells that make sperm. Other medicine groups carry a lower risk. Combining chemotherapy with radiotherapy near the pelvis or testes, or with surgery to reproductive organs, increases the effect.

Age changes the picture considerably. In women, the ovaries contain a fixed store of eggs that falls with age. A young woman may lose some eggs to treatment but still have enough for periods and fertility to return, while a woman nearer menopause may lose her remaining reserve and enter menopause. In men, sperm production often stops or falls during treatment, but the stem cells that make sperm can recover over months or years, more often after less intensive treatment and in younger men. Even when fertility returns, it may be reduced, and in women menopause may come earlier than it otherwise would. Because nobody can predict exactly what will happen for a particular person, the safest approach is to discuss fertility preservation before treatment starts, and to have fertility tested afterwards if you want children. This page describes general patterns and is not a prediction for you.

Temporary effects are common

Periods may stop and sperm counts may drop during treatment, then recover afterwards in many people.

Recovery can take time

For some people it takes months; for others, years. Testing shows what is happening.

Pregnancy is still possible during treatment

Reduced fertility does not mean no fertility. Contraception remains essential.

It cannot tell you whether you will be infertile after your treatment. The categories above are broad, and individual responses vary. Only your oncologist, sometimes with a fertility specialist, can estimate your personal risk.

It also cannot give success rates for having children after treatment or after fertility preservation. These depend on many individual factors and should be discussed with a specialist.

Targeted and immunotherapy medicines

Effects of many newer medicines on fertility are less well known. Ask your team what is known.

Hormone treatments

Hormone-blocking treatment after chemotherapy can delay pregnancy plans and affect periods.

Returning periods and fertility

Periods returning does not always mean normal fertility. Testing gives more information.

Sperm quality

Sperm may return in reduced numbers. A fertility specialist can advise on options.

Children and teenagers

Treatment before or during puberty can affect later fertility. Ask about options for young people.

Emotional impact

Uncertainty about fertility can be distressing. Counselling helps.

Partners and families

Share information with partners and family so decisions can be made together.

Other paths to parenthood

Donor options and adoption remain possible if fertility does not recover.

How chemotherapy affects the ovaries

A woman is born with all the eggs she will ever have, stored in small sacs called follicles within the ovaries. Over the years, this reserve naturally falls, and menopause happens when it runs out. Chemotherapy damages growing follicles and can also destroy resting ones, reducing the reserve. Short-term, this often stops periods during treatment. Whether periods and fertility come back depends on how many follicles survive. A woman who starts with a large reserve, typically at a younger age, is more likely to keep enough for fertility to return, though her fertile years may be shortened. A woman with a smaller reserve, often nearer her forties, is more likely to lose it altogether. This is why age is such a strong predictor, and why tests of ovarian reserve after treatment can be so useful for planning.

How chemotherapy affects sperm production

In men, sperm are made continuously from stem cells in the testes. Chemotherapy damages the rapidly dividing cells that develop into sperm, so sperm counts often fall sharply within weeks of starting treatment. If the stem cells survive, sperm production can restart after treatment ends, but it may take many months or several years, and counts may not return to previous levels. Some treatments, especially high total amounts of alkylating medicines and high-dose treatment before transplant, can destroy the stem cells, causing permanent infertility. Hormone levels, including testosterone, are often less affected than sperm production, so a man may feel well and have normal sexual function while producing few or no sperm. Only a semen analysis can show whether sperm have returned.

Talking about fertility risk honestly

Doctors often describe fertility risk in broad categories rather than exact figures, because individual outcomes vary. It is reasonable to ask what the categories mean for you, what the uncertainties are, and whether a fertility specialist could give more detail. Honest conversations help people make choices they will not regret later.

What to do next

Ask your oncologist about your fertility risk before treatment, consider preservation if children may matter to you, use contraception during treatment, and ask for fertility testing after treatment when you are ready to plan a family.