Causes of menopause


Menopause occurs when there has been a change in a woman's reproductive hormones and the ovaries have run out of eggs. Menopause can happen naturally and at the expected age, or prematurely, or early. Periods can stop unexpectedly due to primary ovarian insufficiency (POI), or menopause can occur 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, or 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 40-45.

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

Natural menopause

Natural menopause occurs at the expected age of around 45-55 years (the average in Australian women is 51-52 years). It is considered a natural life event due to the ovaries running out of eggs.

As a woman approaches her final menstrual period, she may:

  • 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
  • develop or have more painful periods
  • develop or experience premenstrual syndrome (PMS).

Approximately 20% of women will have no symptoms of menopause. Other women may have symptoms of menopause such as hot flushes, sleep disturbance, vaginal dryness, mood changes, sore breast, bloating, headaches, and reduced coping capacity.

female reproductive system, pelvic, uterus

Primary ovarian insufficiency (POI)

When periods stop spontaneously either prematurely or early, this is referred to as primary ovarian insufficiency (POI). This can be the result of a number of conditions, or an unknown cause. This needs to be investigated by a specialist in women's health who has expertise in this area; usually an endocrinologist (hormone specialist) or a gynaecologist. Several blood tests are usually performed to confirm the POI and to try to find a cause.

It is very important that women with POI have some form of hormone therapy until around the age of expected menopause to help avoid early onset of potential long-term risks such as osteoporosis (unless there are medical reasons they are unable to use hormone therapy, such as women with a history of breast cancer). The type of hormone therapy is high-dose menopause hormone therapy, or MHT (formerly called hormone replacement therapy, or HRT) or, if appropriate, the combined oral contraceptive pill. For more information about POI go to 'Premature & early menopause'.

Induced menopause

Chemotherapy-induced & radiotherapy-induced menopause

Menopause can happen as a result of chemotherapy and/or radiotherapy treatment for cancer because the treatments can cause ovaries to stop working. Sometimes periods can stop, but can return after some months, depending on a woman's age and the type of chemotherapy received.

Menopause due to surgery

Removal of ovaries

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

The three female hormones – oestrogen, progesterone and testosterone – are all released from the ovaries. When the ovaries are removed, the levels of oestrogen and testosterone in the body fall; within 24 hours of the surgery, their levels fall by 50%. This can result in severe menopausal symptoms that interfere with daily life. Some symptoms start within 48 hours of surgery, while others can develop later.

Why both ovaries may be removed

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

  • endometriosis – severe endometriosis causing chronic pelvic pain and impairment of quality of life, usually with a hysterectomy
  • 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 – can 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.

Hysterectomy

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.

Ten to 12% of women who have a hysterectomy and keep their ovaries have menopause about 1-4 years earlier than their expected menopause. For most 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 menopause hormone therapy, or MHT (formerly called hormone replacement therapy, or HRT). Your doctor can advise you about the risks and benefits of using MHT.

If the ovaries have been removed (oophorectomy) but not the uterus (hysterectomy), MHT will include both oestrogen and progestogen, with or without testosterone. Progestogen is used to protect against uterine cancer. When a woman is on oestrogen therapy, she needs a progestogen to stabilise the lining of the uterus, which reduces her risk of cancer of the uterus.

If both an oophorectomy and hysterectomy are performed, oestrogen and possibly testosterone are needed. Progestogen is not needed, as there is no risk of cancer of the uterus. The hormone therapy is best started within 24–48 hours after surgery.

Sometimes MHT is not an option after surgical menopause, perhaps because of a woman's increased risk of breast cancer, or a clotting condition such as Factor V Leiden mutation, which increases the risk of deep vein thrombosis (DVT). 

The alternatives to MHT may include:

  • some complementary therapies, although there is no evidence to support their use in surgical menopause – for more information go to 'Herbs used in the management of menopause'
  • 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 more easily. This arises because of the drop in oestrogen levels. 

Menopause in younger women can also increase the risk of earlier development of cardiovascular disease (diseases of the heart and blood vessels, such as stroke). Low levels of oestrogen over a longer time can lead to an increased risk of heart disease, other vascular disease, decreased cognition and an increased risk of dementia.

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

Reactions to surgical menopause

A surgical menopause can be a difficult time for many women. Menopausal 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. This includes 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 might 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.

References

  1. Davis SR, Lambrinoudaki I, Lumsden M, Mishra GD, Pal L, Rees M et al. Menopause. Nat Rev Dis Primers. 2015;1:150042015, doi: 10.1038/nrdp.2015.4.

  2. Faubion SS, Kuhle CL, Shuter LT, Rocca WA. Longterm health consequences of premature or early menopause and considerations for management. Climacteric. 2015;18(4):483–91.

  3. Torrealday S, Pal L. Premature menopause. Postmenopausal endocrinology. Endocrinol Metab Clin North Am. 2015;44(3):543–57.

  4. Rodriguez M, Shoupe D. Surgical Menopause. Postmenopausal endocrinology. Endocrinol Metab Clin North Am. 2015;44(3):531–42.

  5. Maclaran K, Panay N. Current concepts in premature ovarian insufficiency. Women's Health. London. 2015;11(2):169–82. doi: 10.2217/whe.14.82.

Last updated 26 September 2018 — Last reviewed 17 December 2017

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 December 2017.

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