Perimenopause Causes & Symptoms Explained

A guide to perimenopause

Much like the rest of our body, as ovaries age, they don’t function as well as they used to. This can lead to fluctuations of hormones and overall, less oestrogen being produced.

This change in hormone levels eventually leads to menopause, where your period stops completely, and you reach the end of your fertile years. However, before you reach menopause, you go through a stage known as perimenopause.

What is perimenopause?

Perimenopause is the transition phase before menopause and can last anywhere from two to eight years, with an average of four years. During this time, hormone levels, particularly estrogen and progesterone, fluctuate, leading to symptoms like hot flushes, poor sleep, mood changes, and brain fog (1).

As hormone levels vary, periods can become irregular, either shorter or longer, heavier or lighter, and sometimes even skipped for months. These fluctuations can make symptoms unpredictable, often worsening for a few months and then improving. This variability can make it difficult to diagnose, with some women mistakenly being treated for conditions like depression rather than perimenopause.

Understanding that symptoms may come and go due to these hormonal changes is key in managing perimenopause effectively.

The difference between perimenopause and menopause

Perimenopause is when you have symptoms associated with fluctuating hormone levels, and your periods may be irregular, but they have not stopped. Menopause, on the other hand, is defined as the point in a woman’s life where she has gone 12 consecutive months without a menstrual period, vaginal bleeding or spotting (2).

Perimenopause normally commences in a woman’s 40s and lasts several years. Menopause usually occurs between the ages of 45 and 55, but the average age in the UK is 51 for caucasian women (2). However, there are variations in the average age of menopause depending on ethnicity. For women of African and Caribbean descent, the mean age of natural menopause is 49, and for Pakistani women, the average age is 47 (3).

Can perimenopause be diagnosed?

Perimenopause is usually diagnosed based on symptoms alone, and in most cases, blood tests are not necessary. However, each woman’s experience is unique, and in certain situations, hormone tests may be needed.

Learn more about diagnosing menopause.

When to consider hormonal blood tests:

Under 40 years old: If a woman presents with perimenopausal symptoms before the age of 40, blood tests are recommended to rule out early menopause. Early menopause should be identified promptly to start HRT (hormone replacement therapy) and prevent complications such as cardiovascular disease and osteoporosis.
Ages 40-45: Blood tests may be helpful if a woman presents with perimenopausal symptoms (4).

Secondary causes of symptoms

Perimenopausal symptoms like fatigue, weight gain, and hot flushes can overlap with conditions such as anaemia or an underactive thyroid. A wellness check, which includes blood tests to check for these secondary causes, can be very helpful in identifying and addressing other conditions that may be contributing to or worsening perimenopausal symptoms.

What causes perimenopause?

Perimenopause is caused by a gradual decline in estrogen, but this decrease happens in an unpredictable and fluctuating way. Estrogen levels can drop significantly at times, followed by temporary increases before dropping again. These hormone fluctuations contribute to the irregular periods and a wide range of menopause symptoms that many women experience during this transition.

When does perimenopause usually happen?

There is no “one size fits all” when it comes to perimenopause. The age at which it begins can vary significantly from woman to woman, influenced by factors like ethnicity and family history (especially your mother’s age at menopause) (5).

On average, women start to notice symptoms and changes in their periods in their 40s (1). However, some women may experience premature menopause (before 40), known as premature ovarian insufficiency, and will notice perimenopausal symptoms earlier.

Perimenopause can last several years before reaching menopause.

How do I know if I’m in perimenopause?

Perimenopause signs can be subtle at first. Common changes include:

Irregular periods: Cycles may become longer, shorter, or skip entirely, with changes in flow (lighter or heavier).
Hormonal symptoms: As oestrogen levels drop, you may experience a variety of symptoms. Oestrogen receptors are found throughout the body, so a reduction in oestrogen can lead to symptoms like dry eyes, brain fog, mood swings, palpitations, joint pain, urinary issues, and vaginal dryness (1).

You’re considered to have reached menopause when you’ve gone 12 consecutive months without a period or any vaginal bleeding.

Early perimenopause

In the early stages of perimenopause, your periods may still be fairly regular, but you could start noticing subtle changes. These might include:

Cycle changes: Your menstrual cycle may begin to fluctuate, with periods becoming either longer or shorter. You might also notice that the time between ovulation and your period (called the luteal phase) becomes shorter. This happens because progesterone levels start to drop, particularly when you don’t ovulate in a given cycle (6)
Changes in period flow: Your period flow may also change, becoming heavier or lighter than usual. Some women also experience spotting before their period starts.
Hormonal shifts: As oestrogen and progesterone fluctuate, you may feel the effects with mood swings, hot flushes, and trouble sleeping. These early hormonal changes can have both physical and emotional impacts (1).

Late-stage perimenopause

If you're still having periods but they become more irregular, such as skipping some or having intervals of 60 days or more between them, you’re likely in late perimenopause (7). This phase usually occurs in your late 40s to early 50s.

As you approach menopause, typically around 6 months before, oestrogen levels begin to drop significantly. During this time, you may notice existing symptoms like brain fog and poor sleep becoming more intense, or you might develop new symptoms such as vaginal dryness (7).

While irregular periods are a key sign of late perimenopause, there are also other physical, emotional, and mental symptoms that may arise as oestrogen continues to fluctuate.

Symptoms of perimenopause

Oestrogen receptors are located throughout the whole body. As a result, lowering oestrogen levels can cause symptoms in practically every organ system. The most common symptoms of perimenopause are:

Anxiety
Brain fog
Hair loss
Headaches
Hot flushes
Irregular periods
Low libido
Mood swings
Night sweats
Palpitations
Rage
Sleep issues
Sore muscles and joints
Vaginal dryness
Weight gain

You may find it useful to keep a symptom diary, keeping note of changes to your menstrual cycle, mood, and other symptoms. This can be particularly beneficial should you reach out for support from a doctor.

Treatment for perimenopause

While perimenopause is a natural part of ageing that can’t be stopped, there are treatments available to help manage its symptoms.

The most effective treatment is HRT (hormone replacement therapy), which typically includes oestrogen and often progesterone, with some women also benefiting from testosterone.

Research shows that HRT can help manage symptoms like hot flushes and mood swings, improving quality of life. It also provides long-term health benefits, such as reducing the risk of cardiovascular disease, supporting bone health, and helping to prevent osteoporosis (8).

Find out more about taking HRT during perimenopause.

How early can menopause start?

For most women, menopause occurs between the ages of 45 and 55. However, menopause can happen in your 20s, 30s, or 40s. Menopause before the age of 45 is called early menopause, and menopause before 40 is called premature menopause (9).

Natural early menopause affects around 5% of women under 45. Premature menopause (also known as premature ovarian failure) occurs in approximately 1% of women under 40 and 0.1% of women under 30 (9). However, the prevalence of premature menopause does vary by ethnicity, with African American and Hispanic women being more likely to experience premature menopause and Japanese and Chinese women being less likely to experience premature menopause (10).

What causes early menopause?

Premature menopause is an indication that the ovaries aren’t working as they should and stop producing eggs earlier than they would naturally from ageing. The cause of premature menopause, which happens before the age of 40, is unknown in 90% of cases (9). However, known causes of early and premature menopause include:

Medical treatments: Chemotherapy or radiation therapy for cancer may damage the ovaries and cause early menopause (11).
Surgery: Removal of the ovaries (oophorectomy) or a hysterectomy can trigger early menopause (11).
Lifestyle factors: Smoking has been linked to an earlier onset of menopause, as it can reduce oestrogen levels (11,12).
Chromosomal abnormalities: Conditions like Turner syndrome can lead to ovarian dysfunction and early menopause (13).
Starting your period earlier: Early menopause is more likely if you had your first menstrual period before the age of 11 (14).
Birth history: If you have never given birth, or have only given birth once or twice, menopause can occur earlier (14).
Medication: Certain hormone medications can bring on early menopause (11).
Weight: Women who are underweight at the age of 35 are nearly 60% more likely to enter early menopause (15).

Is premature menopause hereditary?

You do have a higher chance of premature menopause if other women on your mother’s side of the family experienced menopause earlier than usual. One study found that 37.5% of early menopause cases reported a family history of menopause before the age of 46 compared to only 9% of women who did not go through menopause early (5).

What are early menopause symptoms?

The main symptom of early menopause is your periods becoming irregular (short or longer, lighter or heavier, or not occurring every month) or stopping completely. Other symptoms include those typical of perimenopause and menopause such as hot flushes, night sweats, mood swings and vaginal dryness.

Are there any benefits of early menopause?

Early menopause can reduce your risk of breast cancer and ovarian cancer. This is because these types of cancer are oestrogen-sensitive and linked to higher levels of the hormone. In women who go through early menopause, oestrogen levels are significantly lower.

However, there are also health risks associated with early menopause, including a higher risk of heart disease and cancer for women who enter menopause before 40.

It can also increase the risk of osteoporosis and depression. Women who experience menopause at age 40 or later are about half as likely to experience depression as women who experience premature menopause (16).

Early or premature menopause can also impact a woman's mental and emotional health due to its impact on fertility.

Is there any way to avoid early menopause?

In most instances, when menopause begins is beyond your control. However, some steps may help reduce the risk or delay its onset, especially if lifestyle factors are involved:

Quit smoking: Smoking is one of the most significant risk factors for early menopause. Quitting can help preserve oestrogen levels.
Maintain a healthy weight: Being underweight or overweight can affect hormone balance (17). A healthy diet during menopause and regular exercise can support overall reproductive health.
Manage stress: Chronic stress can affect hormone levels, and research indicates that it may contribute to a reduced age at natural menopause (18).
Monitor family history: If early menopause runs in the family, working with a healthcare provider to monitor hormone levels may allow for early intervention.

When should I see a doctor about perimenopause?

You should see a doctor about perimenopause if you're experiencing bothersome symptoms, such as irregular periods, night sweats, mood changes, or sleep problems, especially if these affect your quality of life.

When it comes to diagnosing menopause, your doctor will evaluate your symptoms, menstrual history, and overall health. No single test can definitively confirm you’ve entered perimenopause. Instead, diagnosing perimenopause involves considering your:

Symptoms
Medical history
Age
Lifestyle

Sometimes, a physical exam can help with a diagnosis, and in some instances, blood tests to measure your hormone levels will provide further insight.

Blood tests for perimenopause and menopause aren't usually necessary for women over the age of 45. We do advise that women under the age of 40 who present with symptoms require hormone blood tests, as it is vital that we identify and treat early menopause early. Women between the ages of 40-45 may benefit from hormone blood tests. Sometimes your doctor may suggest blood tests to ensure that there are no secondary causes which could be exacerbating symptoms, such as an underactive thyroid or anaemia

If you can, it's best to consult a specialist who understands women’s hormonal health and reproductive issues. They can offer personalised care, guide you through managing symptoms, and offer treatments if needed.

At Menopause Care, we have a team of experienced menopause doctors and nurses here to help you navigate perimenopause, menopause, and beyond. If you would like to discuss your symptoms, want to know more about HRT so you can make an informed choice about treatment, or would like specific nutritional or mental health support, book a consultation today.

DisclaimerAt Menopause Care, we ensure that everything you read in our blog is medically reviewed and approved. However, the information provided is not meant to replace professional medical advice, diagnosis, or treatment. It should not be relied upon for specific medical advice.

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