Causes of menopause

Menopause occurs when there has been a change in a woman's reproductive hormones and the ovaries are no longer able to release any eggs.  Menopause can happen naturally and at the expected age, prematurely or early. Periods may stop unexpectedly due to primary ovarian insufficiency (POI), or menopause occurs when the ovaries are removed through surgery (oophorectomy) or because of various treatments for cancer.

Menopause can be classified as natural at the expected age, premature or early. Premature menopause is when the final period occurs before a woman is 40 and early menopause is when the final period occurs before a woman is 45.

Early and premature menopause can occur as a result of induced menopause or primary ovarian insufficiency.

Natural menopause

female reproductive systemNatural menopause occurs at the expected age of around 51-52 – it is considered a natural life event due to ovaries running out of eggs.

As a woman heads towards her final menstrual period, a time known as perimenopause, she may:

  • develop or have more painful periods
  • develop or experience premenstrual syndrome (PMS)
  • have changes to the regularity of her periods – perhaps shorter or longer cycles
  • have changes in the flow of her periods – perhaps heavier or lighter
  • continue with regular periods until they just stop

Approximately 20% of women will have no symptoms except they have no period for 12 months. Other women may have symptoms of menopause such as hot flushes, thinning of the vagina and mood changes.

Primary ovarian insufficiency (POI)

When periods stop spontaneously, either prematurely or early, this is referred to as 'primary ovarian insufficiency'. This can be the result of several conditions or an unknown cause. 

Induced menopause

Chemotherapy & radiotherapy induced menopause

Menopause may happen as a result of chemotherapy and/or radiotherapy treatment for cancer because the treatments can cause ovaries to stop working. 

Menopause due to surgery

Removal of ovaries

Menopause occurs when a woman who is still having periods has surgery to remove both ovaries (oophorectomy).

When the ovaries are removed, the levels of oestrogen and progesterone fall. These are hormones produced from eggs and ovulation (the release of an egg). Because ovaries are the main source of the hormone testosterone, these levels can also drop.

Symptoms after oophorectomy

Within 24 hours of surgery, because levels of oestradiol (the main form of oestrogen produced by ovaries) fall by more than 50% and testosterone levels fall, this can result in severe menopause symptoms that interfere with daily life. Some symptoms start 48 hours after surgery while others may develop later.

Why both ovaries may be removed

The reasons doctors may advise removing both ovaries before the "natural" age of menopause (51-52 years in Australia) include:

  • endometriosis – where uterus tissue forms outside the uterus involving the ovaries and causes chronic pain
  • chronic pain because of pelvic inflammatory disease (PID) – an infection of the uterus, fallopian tubes or ovaries
  • ovarian cancer
  • preventative removal of ovaries because there is a high risk of developing breast or ovarian cancer – may be because of:
    • a strong family history of breast or ovarian cancer
    • the presence of certain genetic variants (BRCA-1 or -2) that identify a woman as having a higher risk of developing breast or ovarian cancer


Sometimes there is confusion about whether having a hysterectomy (the removal of the uterus) will put you into menopause. If your uterus is removed but you still have your ovaries, you will not necessarily go straight into menopause.

10-12% of women who have a hysterectomy and keep their ovaries have menopause approximately one to four years earlier than their expected menopause. For the majority of women menopause occurs at the same time and with the same symptoms as if they had not had a hysterectomy. 

Management & treatment after surgical menopause

Because symptoms of a surgical menopause are likely to be more severe, often the best way to manage and treat symptoms is with hormone replacement therapy (HRT). Your doctor can advise you about the risks and benefits of using HRT.

If the ovaries have been removed (oophorectomy) but not the uterus (womb), HRT will include both oestrogen and progestogen with or without testosterone. Progestogen is used to protect against uterine cancer. Progestogen causes the lining of the uterus to shed and this reduces the risk of cancer of the uterus.

If both ovaries (oophorectomy) and the uterus are removed (a hysterectomy), oestrogen and possibly testosterone are needed. Progestogen is not needed, as there is no risk of cancer of the uterus.

Sometimes HRT is not an option after surgical menopause, perhaps because of an increased risk of breast cancer or a blood clotting condition such as deep vein thrombosis (DVT).  The alternatives to HRT may include:

  • some complementary therapies, although there is not evidence to support their use in surgical menopause – for more information go to menopause and natural and complementary therapies
  • some antidepressant, anticonvulsant and migraine/blood pressure medications which work to reduce hot flushes

Younger women (under 45 years) who experience a surgical menopause are also at increased risk of osteoporosis, a condition in which bones become fragile and can break easily. This arises because oestrogen levels drop, and oestrogen is important for bone density. 

Menopause in younger women can also increase the risk of developing cardiovascular disease (diseases of the heart and blood vessels such as stroke) because low levels of oestrogen over a longer time can cause arteries to harden.

It is important if you experience menopause early or prematurely that you talk with your doctor about the best way to manage both menopause symptoms and your risk of further health complications.

Reactions to surgical menopause

A surgical menopause can be a difficult time for many women. Menopause symptoms are often severe and depression and anxiety are more likely.

How you react can be influenced by the reason for the surgery. If your surgery is necessary because of a diagnosis of cancer, this creates challenges to cope with at the same time as coping with menopausal symptoms. On the other hand, if your surgery is the solution to ongoing chronic pain then a surgical menopause may offer relief.

What's happening in your life will affect your reactions to surgical menopause, these include your age, whether you are in a relationship, whether you have children, whether you wanted to have children or more children and whether you have support and help.

Some women say the impact of surgical menopause is that they no longer feel like a woman, other women feel a sense of freedom from pain and fear. Some women feel they may not be as sexually attractive to their partner and others feel they can be more sexual because they are not worried about pain or heavy bleeding.

No feeling should be dismissed as silly or small. It is important to talk to someone if you are upset and distressed about a surgical menopause. You can ask your doctor for help with symptom relief and with referral to a psychologist to discuss your feelings.

Last updated 24 July 2017 — Last reviewed 02 March 2014

** Currently under review **

This web page is designed to be informative and educational. It is not intended to provide specific medical advice or replace advice from your health practitioner. The information above is based on current medical knowledge, evidence and practice as at March 2014.

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