These substances are produced naturally in the body. Hormones control many of the body’s functions, including how you grow, develop and reproduce. The pituitary gland in the brain releases hormones that tell the body to make sex hormones.

• In females, the major sex hormones are oestrogen and progesterone, which are produced in the ovaries. These hormones control the growth and release of eggs, and the timing of periods (menstruation).
• In males, the major sex hormone is testosterone, which is produced mainly in the testicles. Testosterone helps the body make sperm.

The egg travels from the ovary into the fallopian tube. Here it can be fertilised by a sperm, which is ejaculated from the penis into the vagina during sexual intercourse. If the egg is fertilised, it will implant itself into the lining of the uterus and grow into a baby. After the egg is fertilised by the sperm, it’s called an embryo.

As females get older, the number of eggs in the ovaries drop and the ovaries produce less oestrogen and progesterone. When the egg numbers and the levels of these hormones fall low enough, periods will stop. This is known as menopause. This is the natural end of the female reproductive years and it usually happens around the age of 45–55.

• ovaries  – two small, walnut-shaped organs in the lower part of the abdomen. They contain follicles that hold immature eggs, which eventually become mature eggs. The ovaries also make the hormones oestrogen and progesterone.
• fallopian tubes  – two long, thin tubes that extend from the uterus and open near the ovaries. These tubes carry sperm to the eggs, and the eggs from the ovaries to the uterus.
• uterus (womb)  – a hollow muscular organ where a fertilised egg is nourished to form a baby. The inner lining of the uterus is known as the endometrium. Each month if an egg is not fertilised, some of the lining is shed and flows out of the body (menstruation or monthly period). The uterus is joined to the vagina by the cervix.
• cervix (neck of the uterus)  – the lower, cylinder-shaped entrance to the uterus. It produces moisture to lubricate the vagina. It also holds a developing baby in the uterus during pregnancy and widens during childbirth.
• vagina (birth canal)  – a muscular channel that extends from the opening of the uterus (the cervix) to the vulva. This is the passageway through which menstrual blood flows out of the body, sexual intercourse occurs and a baby is born.
• vulva  – the external part of a woman's sex organs.

• testicles (testes) – two small, egg-shaped glands that make and store sperm, and produce the hormone testosterone. This is responsible for the development of male characteristics, sexual drive (libido) and the ability to have an erection.
• scrotum  – the loose pouch of skin at the base of the penis that holds the testicles.
• epididymis  – a tightly coiled tube attached to the outer surface of each testicle. Sperm travel from the testicles through the epididymis to the spermatic cord.
• spermatic cord and vas deferens  – the tubes running from each testicle to the penis. They contain blood vessels, nerves and lymph vessels, and carry sperm towards the penis.
• seminal vesicles  – glands that lie close to the prostate and produce fluids that make up part of the semen.
• prostate  – a small gland about the size of a walnut that produces fluids that form part of semen. It is located near the nerves, blood vessels and muscles that control bladder function and erections.
• penis  – the main external sex organ, through which urine and semen pass out of the body. Semen is made up of sperm and other fluids, and is ejaculated from the penis.

Infertility is defined as difficulty getting pregnant (conceiving). This may result from female or male factors, or a combination of both.

For females under 35, the term usually refers to trying unsuccessfully to conceive for 12 months. If a female is 35 or over, the term is used after six months of trying. Infertility is more common than many people realise – it affects one in six Australian couples.

Cancer and its treatment may cause fertility problems. This will depend on the type of cancer and treatment you have. Infertility after treatment may be temporary, lasting months to years, or permanent.

Female reproductive organs – some cancer treatments, especially chemotherapy and radiation therapy, may damage the ovaries and decrease the number of available healthy eggs. Radiation therapy may also damage other reproductive organs.

Cancer treatments can reduce the level of hormones produced in the brain and the ovaries. Sometimes the reproductive organs are removed during surgery. All of these treatments can lead to early menopause.

Male reproductive organs – some cancer treatments, especially chemotherapy and radiation therapy, may affect sperm quantity (low numbers of sperm are made), quality (the sperm do not work properly) or motility (the sperm move poorly). Sometimes, the reproductive organs are damaged or removed during surgery.

This describes the procedures that someone can use to help maintain their ability to have children, for example, freezing eggs, embryos or sperm. These procedures are usually done before you have cancer treatment that may affect your fertility, but some are also used after treatment.

Age is one of the most important factors that influences the impact of cancer treatment on fertility.

Female age and fertility – females are born with all the eggs they will have in their lifetime. As they age, the number of eggs reduces. Fertility starts to decline after 30 and the decline speeds up after 35. It then becomes harder to conceive and the risk of genetic problems in the eggs increases.

From the early 40s, although a woman still has regular periods, it is difficult to conceive a child because of poor egg quality. After menopause, it is no longer possible to conceive a child naturally.

The impact of cancer treatments can vary with age. Before and after puberty, the effect of chemotherapy and radiation therapy on fertility can range from mild to severe, depending on the drugs used and the dose. Before puberty, high doses of drugs or radiation may sometimes cause enough damage to the ovaries that both the start of puberty and future fertility are affected.

After puberty, treatment to the ovaries can cause periods to stop. Even if periods return after treatment, some women may experience early menopause.

Male age and fertility – The quality and quantity of sperm decreases with age. This means it will take longer for an older man’s partner to get pregnant. Before and after puberty, chemotherapy and radiation therapy may affect sperm production and may cause infertility. The effect of radiation will depend on where in the body the radiation is given and the dose.

This is a very personal decision. A cancer diagnosis may affect the way you think and feel about having a child. If you have a partner, you may want to discuss your family plans together. Fertility clinics often have counsellors who can talk through the pros and cons of your situation.

This depends on many factors, including the type of cancer and type of treatment. Some cancer specialists advise waiting between six months and two years after treatment ends. This may be to allow your sperm or eggs to recover, and to ensure you remain in good health during this time. It’s best to discuss the timing and suitable contraception with your doctor.

For some fertility treatments, you will need to take extra hormones or stimulate your hormones. If you have a hormone-sensitive cancer, you may be given hormone receptor blockers to reduce the risk of the cancer coming back. Discuss the potential risks of particular fertility treatments with your cancer or fertility specialist. Taking hormone receptor blockers during egg collection can help reduce the risks.

Research shows that for most cancers pregnancy does not increase the chances of cancer coming back (recurring). However, sometimes it is hard to do any follow-up tests for cancer when a woman is trying to conceive or is pregnant. Research is continuing, so it’s best to discuss this issue with your specialist.

Studies to date suggest that survival rates for people who have children after cancer treatment are no different from people who don’t have children after treatment.

Studies show that if one or both parents have a history of cancer, their child is at no greater risk of getting cancer than anyone else. A small percentage of some cancers (up to 5%) are caused by an inherited faulty gene from either the mother or father. This is known as familial cancer. The faulty gene increases the risk of cancer, but even then, it does not mean that a child will inherit the gene and develop cancer.

A genetic counsellor is the most qualified person to give you up-to-date information about the genetic risks of cancers for family members. For more information call Cancer Council on 13 11 20.

Being diagnosed with cancer during pregnancy is uncommon, but it can happen.

It may still be possible to have cancer treatment during pregnancy. It’s best to discuss the potential risks and benefits with your oncologist before treatment begins. In some cases, treatment can be delayed until after the baby’s birth. For some cancers, chemotherapy may be safely used after the first trimester (12 weeks), usually with a break of a few weeks before the birth.

Some people diagnosed with cancer in the early weeks of pregnancy decide to terminate the pregnancy so they can start treatment immediately, while others who are diagnosed later in the pregnancy choose to have their baby before the due date.

You will be advised not to breastfeed during chemotherapy, targeted therapy or immunotherapy as drugs can be passed to the baby through the breastmilk. If you are having radiation therapy, talk with your doctor about whether it is safe to continue breastfeeding during your treatment course.

Fertility is an important part of health for everyone. But your doctor may not discuss whether you want children in the future if they make assumptions based on your age, sexual orientation, gender and sex characteristics or focus on starting treatment immediately. If fertility matters to you, let your health professional know.  

There are several people you may see to discuss fertility, including a fertility specialist, paediatric gynaecologist, endocrinologist, fertility counsellor and urologist, among others. Let the fertility clinic or specialist know that you are having treatment for cancer so that they give you an appointment as soon as possible. Your cancer care team may also be able to help you get an appointment quickly.