Common causes of female infertility

There are many causes of infertility or subfertility (reduced fertility), and it is very common among couples everywhere.

The cause can involve one or both partners. As a general rule, in about one-third of cases, infertility is due to a cause involving only the male partner, in another one-third of cases, infertility is due to causes involving both the male and female and in the remaining one-third of cases, infertility is due to a cause involving only the female partner.

Causes of infertility or subfertility include the following:


Increasing age is a significant cause of subfertility in women. As a woman gets older, the number of eggs in her ovaries decreases rapidly, and those remaining are of a poorer quality. A woman’s fertility rapidly declines once she enters her 30s.

For example, a healthy 30-year-old woman has about a 20% chance per month of successfully getting pregnant when not using contraception. By age 40, however, this reduces to about 5% per month.



Alcohol, smoking, drug use, and excess weight are all common causes of subfertility and infertility. Adopting a healthy lifestyle is the first step in optimising your chances of becoming pregnant. These are the only risk factors for subfertility that you have the power to change. For more on this, see Your Health While Trying For A Baby.

Ovulatory Problems

Stress, anxiety, excessive weight loss/ weight gain and strenuous exercise may all cause irregular ovulation. Hormonal imbalances such as high levels of the hormone Prolactin may also affect ovulation.

Polycystic Ovary Syndrome (PCOS) is a common female health problem in which there is an imbalance in a woman’s hormone levels. It is characterised by the presence of small cysts on the ovaries and greater than normal levels of male-type hormones in the body. Women with PCOS usually experience irregular ovulation, which reduces chances of pregnancy.

Tubal Problems

The Fallopian tubes allow the transport of the released egg from the ovary into the womb. Anything that blocks these tubes, and hence the egg from travelling, can result in fertility difficulties. Causes of blockage include scarring of the tissue inside the tubes from previous surgery or from Pelvic Inflammatory Disease (PID).


Endometriosis is a condition where the endometrial tissue, found in the lining of the womb, grows in areas outside of the womb. This tissue can be found on the ovaries, in the Fallopian tubes, on the bowel and in the pelvic cavity. Each month, hormones released by the body cause this tissue to thicken, resulting in pain, inflammation and scarring.

Sexual Dysfunction

Some women experience involuntary tightening of the walls of the vagina during sex. This is called ‘vaginismus’. Vaginismus can interfere with sex by causing pain and soreness during penetration and for some women it can make penetrative sex impossible. If penetrative sex is not possible, pregnancy cannot occur.


In many cases no reason for subfertility can be detected. Sometimes a combination of the above factors leads to subfertility.