Reproduction and fertility

Reproduction is the way we produce babies. Knowing how your body works may help you understand how fertility problems happen and why some people are unable to conceive.

Learn more about:

How reproduction works

The female and male reproductive systems work together to make a baby. The process involves combining an egg (ovum) from a female and a sperm from a male. This is called fertilisation.

Role of hormones

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.

Ovulation

Each month, from puberty (sexual maturation) to menopause (when periods stop), one of the ovaries releases an egg. This is called ovulation.

Pregnancy

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.

Menopause

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.

Factors that affect fertility

Some of the common factors that affect fertility include:

age – fertility naturally declines with age
weight – being significantly underweight or overweight
smoking – active and passive smoking can harm reproductive health
alcohol – drinking alcohol may affect fertility and make it harder to conceive
other health issues – endometriosis, fibroids, pelvic disease, certain hormone conditions or cancer.

See Key questions to learn more about how cancer affects fertility.

Transgender, non-binary or intersex?

This information has been developed based on guidance and evidence in male and female bodies. If you are a non-binary or transgender woman, transgender man or person with an intersex variation, this information is still relevant to you if you have a cervix and a uterus or testicles and a penis – but your experience may be slightly different.

For information specific to your situation, speak to your doctor.

Listen to our podcasts on Sex and Cancer and Coping with a Cancer Diagnosis

This information was last reviewed in May 2020. View who reviewed this content.

Dr Ying Li, Gynaecologist and Fertility Specialist, RPA Fertility Unit, Royal Prince Alfred Hospital, NSW; Dr Antoinette Anazodo, Paediatric and Adolescent Oncologist, Sydney Children’s Hospital and Prince of Wales Hospital, NSW, and Lead Clinician for Youth Cancer NSW/ACT; Paul Baden, Consumer; Dawn Bedwell, 13 11 20 Consultant, Cancer Council Queensland; Maurice Edwards, Special Counsel, Watts McCray Lawyers, NSW; Helena Green, Clinical Sexologist and Counsellor, InSync for Life, WA; Dr Michelle Peate, Program Leader, Psychosocial Health and Wellbeing Research (emPoWeR) Unit, Department of Obstetrics and Gynaecology, Royal Women’s Hospital, The University of Melbourne, VIC; A/Prof Kate Stern, Gynaecologist and Reproductive Endocrinologist and Head, Fertility Preservation Service, Royal Women’s Hospital Melbourne, The University of Melbourne, VIC; Prof Jane Ussher, Chair, Women’s Health Psychology, Translational Health Resea ch Institute (THRI), School of Medicine, Western Sydney University, NSW; Renee Van Den Bosch, Consumer.

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