What is Menopause?

Menopause marks a new phase of life for a woman. In the simplest of terms, it means that you have gone 12 full months without a period.

This article explains more about the phases of menopause, including perimenopause. We explain when you might expect to become perimenopausal and what is happening to your body during this time. For more information about symptoms, diagnosis and treatment options explore the rest of our perimenopause and menopause resource area.

What is menopause?

Menopause marks a new phase of life for a woman. In the simplest of terms, it means that you have gone 12 full months without a period.

The menopause affects all women and it can also affect transgender and non-binary people too.

What are the stages of menopause?

The four stages of menopause reflect the different phases in a woman’s life:

  1. Premenopause

Premenopause is the phase of life when you will have no symptoms and your periods will be generally regular. Within the body, the ovaries are fully functioning and hormone production is ongoing. For many women this phase begins in their early teens and continues through until their early- to mid-40s. That's not the case for everyone though as premenopause can end a lot earlier for some women.

  1. Perimenopause

The months and years leading up to menopause are defined as ‘perimenopause’ and on average, in the UK, this will begin around the age of 45.

It’s during this time that your periods will start to become more infrequent and irregular. You may experience the symptoms we commonly think of as menopausal such as hot flushes, night sweats and low mood. These vary enormously from woman to woman. For some women, these symptoms are mild and last only a few months. For others the symptoms are severe and can impact other areas of their life for many years before their periods stop. 

TIP: Use our free, downloadable symptom checker to track your symptoms to get an indication of whether you are perimenopausal. If these symptoms are impacting your day-to-day life then it’s best to visit your GP or a menopause specialist.

  1. Menopause 

Your menopause will actually be a single point in time - one day! It refers to the one day directly after 12 months since your last period. 

Up until that point you are perimenopausal, and after that day you are postmenopausal. In both the UK and the US, the average age that a woman reaches menopause is 51-years old.

  1. Postmenopause

This is the period of time after your diagnosis of menopause. It doesn’t necessarily mean that your menopausal symptoms will have ended, but it does mean that your periods will have stopped. 

What causes menopause?

The cause of menopause is a natural process as part of ageing when our body's hormone production begins to change. The exception to this is if surgery or chemotherapy causes an early menopause.  

Understanding the role of hormones in menopause

The reason that we go through menopause is due to the changes to hormones in our body.

As we age our hormone levels drop as the production of these hormones slows up. These hormones are really important to how we feel, so it is the lower levels of hormones which cause menopausal symptoms and affect quality of life. This is also why Hormone Replacement Therapy (HRT) is a popular choice of treatment for women in menopause. 

Let’s take a look at each of the hormones which are important for women:


Oestrogen is the umbrella term used for the three female sex hormones, responsible for egg production and the reproductive process:

  • Oestradiol, needed for reproduction
  • Oestriol, the primary hormone during pregnancy
  • and Oestrone, the main hormone produced by the body post-menopause. 

It can’t be underestimated the impact that oestrogen plays in our overall health.

Women have oestrogen receptors all over their bodies and this hormone plays a vital part in all of our body systems, which is why there can be so many different symptoms of the menopause caused by low oestrogen levels. This includes hot flushes, night sweats, trouble sleeping, vaginal dryness and weight gain. Oestrogen also has protective benefits for our bones, our heart health and brain health - see our interview here with leading expert and author of 'Oestrogen Matters' Dr Avrum Bluming.


Progesterone is produced in the ovaries after ovulation each month and regulates the menstrual cycle.  It also helps to prepare and maintain the womb for pregnancy. Lower levels of progesterone might cause you to get migraine headaches, mood changes or irregular bleeding. If you choose to take HRT for your menopausal symptoms then progesterone is needed as part of this only if you still have a uterus.

Did you know: Women produce three to four times as much testosterone as oestrogen before the menopause and it decreases naturally through our lives?


Women are often surprised to hear that it’s not just men that produce testosterone.

Women also produce small amounts, partly in the ovaries and partly in the adrenal glands.  Women produce three to four times as much testosterone as oestrogen before the menopause and it decreases naturally through our lives.

Testosterone production reduces more drastically in women who have had surgical or medical menopause, or who have had premature menopause. In these cases, testosterone production decreases by more than 50%, according to the British Menopause Society

Our testosterone levels impact so many aspects of our health and wellbeing: our mood, energy levels, concentration and our libido. 

That’s why lower levels of testosterone can make it harder to lose weight in midlife, reduce your desire to have sex, and give you that exhausted and low feeling that even a good night’s sleep doesn’t seem to help.

In the UK replacement testosterone isn't licensed by the UK regulatory bodies. This means that the medical specialist who prescribes you testosterone needs to be prepared to prescribe it 'off-license'. So while testosterone is available on the NHS and privately from specialists it may be harder for you to receive the prescription from an NHS doctor unless they are familiar with prescribing testosterone and/or a menopause specialist.

Ideally you need to be established on oestrogen before adding testosterone (although some clinics do start oestrogen/progesterone and testosterone all together).

For more information about testosterone, we have a great article written here by Dr Philippa Kaye, and for more information about how to replace lost hormones, take a look at our article on treatment options here.

What happens to our bodies?

The cells in our body thrive on oestrogen (and progesterone/testosterone), so when levels fluctuate and fall during the perimenopause and menopause it can trigger many different changes in our bodies.

Some women experience psychological symptoms, others physical symptoms and many will experience both. 

TIP: Want to assess your symptoms? Use our free downloadable symptom checker which includes lots of detailed information about each symptom. 

What is the average age of menopause?

Average age of menopause

The average age of menopause in both the UK and US is around 51 years old, with perimenopause usually beginning in the mid-40s.

Early menopause

For around 1 in 100 women menopause will happen much earlier and occur under the age of 40. This early menopause is medically defined as ‘premature ovarian insufficiency’. If you go through early menopause you may experience perimenopausal symptoms under the age of 40. 

Menopause can affect women in their 20s and 30s and even teenagers too. Because of this, there is no youngest age for menopause.

Surgical menopause

Sometimes menopause can happen more suddenly and before the natural ageing process.

This can be due to surgery - for example if the ovaries are removed in a hysterectomy. Or it can be because ovaries are damaged, such as from chemotherapy to treat cancer. 

READ A REAL-LIFE STORY: Our founder Katie Taylor shared her experiences of surgical menopause through hysterectomy in this article.

How long does menopause last?

The length of each stage of the menopause transition varies for each woman. 

The average length of perimenopause is approximately four years. Some women may only be in this stage for a few months, while others will be in this transition phase for more than four years - and perhaps up to ten years. 

How do you know you’re in menopause?

If you have gone more than 12 months without having a period, you are no longer perimenopausal and you are officially classed as having gone through the menopause. Confusingly then, menopause is actually only one single day - the day that follows 12 months without a period. From that point on you are post-menopausal.

Use our free symptom tracker to assess yourself against the 34 symptoms of menopause.

Your doctor should be able to diagnose perimenopause or menopause by hearing about your symptoms. A blood test may be offered if you are under 45-years-old. If you are booking an appointment with your GP to discuss your symptoms then this article will help you prepare everything you need to take with you.

Ready to look at your treatment options? Take a look at our information on treatment options all about the choices that are available to you including HRT, lifestyle changes, supplements and nutritional advice and ways to manage stress, sleep and more.

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