Five causes of female infertility

There are many reasons why women experience difficulty in conceiving. we discuss five common causes. By Kirsten Braun

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A woman's age is the most significant factor influencing her fertility. Women are born with a fixed number of eggs and so as they age so do their eggs. A woman's fertility starts to decline in her early 30s and by age 35 it has dropped by approximately 40%. By age 40 a woman's fertility has declined even further. In addition, as women age conditions like endometriosis can also progress to a level where they may impact on fertility as well (see endometriosis below). Unfortunately, there appears to be a lack of recognition of the impact that age has on fertility. Celebrities having babies in their 40s, for example, has given many women the impression they can leave their childbearing to later in life. Similarly, many women falsely believe that infertility treatments like IVF can overcome any fertility issues. The latest figures on assisted reproductive technology in Australia and New Zealand show that for women aged 30-34 years the chance of a live birth per treatment cycle was 25.3%. For women aged 35-39, this percentage dropped to 16.9% and for women 40-44 years it was only 6.6%.

Polycystic ovarian syndrome (PCOS)

PCOS is a hormone imbalance which results in disrupted menstrual and ovulation cycles. It is the most common cause of infertility due to anovulation (no ovulation or egg is released). The name of the condition comes from the presence of tiny cysts on the outside of the ovaries. While many women have polycystic ovaries, not all women have polycystic ovarian syndrome. Women with PCOS have additional symptoms including irregular periods, excess weight (particularly in the tummy area), excess hair on the face and body, acne and male pattern baldness. It is estimated that 30% of infertile women suffer from PCOS.


Endometriosis is a condition in which the tissue that lines the uterus (endometrial tissue) grows in other parts of the body, usually in the pelvis. This stray endometrial tissue bleeds in the same way as the lining of the uterus, except the blood/tissue is trapped causing irritation and inflammation. Scar tissue can form resulting in adhesions which can stick pelvic structures together. The most common symptoms of endometriosis are period pain and/or pelvic and abdominal pain. Endometriosis can affect fertility by damaging the ovaries so that ovulation cannot occur. Similarly, damage and/or blockages to the inside of the fallopian tubes can impede the journey of the egg to uterus. It is also thought that endometriosis can have an impact on the lining of the uterus, affecting the implantation of a fertilised egg. If women experience pain during sex from endometriosis they might also be reluctant to have sex, reducing their chances of getting pregnant.


A woman's weight is an important consideration in her fertility. Women who are underweight and/or have a low percentage of body fat (ie., athletes) can experience irregular menstrual cycles and issues with ovulation. Being overweight or obese can also interfere with normal menstruation and ovulation. In addition, overweight and obese women also have a higher risk of miscarriage and other pregnancy complications and a lower success rate with infertility treatments such as IVF. Women who find it difficult to lose weight should be assessed to see if they have PCOS (see above) as this is a common symptom. Women can often improve their chances of pregnancy by relatively small changes to their weight. For example, in women who are overweight or obese, a 5% weight loss can be enough to restore a regular menstrual cycle and ovulation.

Sexually transmitted infections (STIs)

If a STI such as chlamydia or gonorrhea goes untreated it can lead to pelvic inflammatory disease (PID). PID is the infection or inflammation of the organs and tissues in the pelvis. Unfortunately, women infected with a STI, particularly chlamydia, don't always experience any symptoms or the symptoms are vague so they do not seek treatment. If PID is left untreated it can cause scarring in the fallopian tubes which can narrow them, blocking the path of the egg. If a fertilised egg becomes trapped in a blocked fallopian tube an ectopic pregnancy can occur (where the foetus develops outside the uterus). This is a serious, potentially life-threatening health condition that requires immediate medical attention. Studies suggest that one episode of PID decreases a woman's chance of a successful pregnancy by 10%. After two or more episodes of PID a woman's risk of becoming infertile is about 50%.

Last updated: June 2014

©Women's Health Queensland Wide Inc. This article was written by Kirsten Braun and reviewed by the Women's Health Queensland Wide editorial committee. It was published in Health Journey 2014 Issue 2.






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