How to Know If You Are in Perimenopause: Testing and Signs

Many women wonder if the changes they are experiencing signal the beginning of perimenopause. Unfortunately, confirming perimenopause is not as simple as taking a single test. This guide explains what research tells us about recognizing and diagnosing perimenopause.

When Does Perimenopause Typically Start?

According to data from the North American Menopause Society and the Study of Women's Health Across the Nation (SWAN), which has been tracking women since 1994:

The average age for perimenopause onset is 47 years old
The typical range is 40 to 55 years
Perimenopause usually lasts 4 to 8 years before menopause
Some women experience symptoms earlier, especially those who smoke

Research from the Melbourne Women's Midlife Health Project (1991-2004) and the Massachusetts Women's Health Study (1980s-1990s) identified factors affecting timing:

Genetics: If your mother had early perimenopause, you may too
Smoking: Smokers enter perimenopause 1 to 2 years earlier on average
Body weight: Very low body weight is associated with earlier onset
Medical treatments: Chemotherapy or pelvic radiation can trigger earlier menopause

The Challenge of Hormone Testing

Why Blood Tests Are Not Definitive

Many women ask their doctors for blood tests to confirm perimenopause. However, the American College of Obstetricians and Gynecologists (ACOG), in guidelines established in the 2000s and maintained through current practice, states that hormone levels are generally not useful for diagnosing perimenopause in women over 45.

Here is why:

Hormones Fluctuate Dramatically Research tracking hormone levels in perimenopausal women, including studies from the 1990s and the ongoing SWAN study, found:

FSH levels could vary by 300% from week to week
Estrogen levels showed similar variability
A single blood test only captures one moment in time

"Normal" Ranges Overlap Perimenopausal hormone levels overlap significantly with premenopausal levels. A woman could test in the normal range one week and show perimenopausal levels the next.

When Testing May Be Helpful

Blood tests can be useful in specific situations:

Women under 40 with symptoms (to evaluate for premature ovarian insufficiency)
Women who have had a hysterectomy and cannot track periods
Ruling out other conditions like thyroid disorders
Women taking hormonal birth control who cannot assess symptoms naturally

Tests your doctor might order:

FSH (Follicle Stimulating Hormone): Elevated levels suggest declining ovarian function
Estradiol: Measures estrogen levels
AMH (Anti-Mullerian Hormone): Indicates ovarian reserve
TSH: Rules out thyroid problems, which can cause similar symptoms

Newer Testing Options

Home hormone tests have become popular, but reviews from medical organizations caution that:

Single-point-in-time testing has significant limitations
Results can be misleading due to normal hormone fluctuations
They should not replace medical evaluation

Reliable Signs of Perimenopause

Research consistently identifies certain symptoms as indicators of perimenopause:

Menstrual Changes (Most Reliable Indicator)

According to SWAN study data published across multiple papers since 2000, the most reliable early sign of perimenopause is changes in your menstrual cycle:

Early Perimenopause

Cycles varying by 7 or more days from your normal pattern
Heavier or lighter periods than usual
Shorter or longer cycles

Late Perimenopause

Missing 2 or more periods in a row
Cycles longer than 60 days
Irregular bleeding patterns

Vasomotor Symptoms

Research from the Melbourne study and others found that approximately 80% of women experience vasomotor symptoms (hot flashes and night sweats) during perimenopause:

Hot flashes: Sudden feelings of heat in the upper body, often with flushing and sweating
Night sweats: Hot flashes that occur during sleep, often disrupting rest

Sleep Disturbances

Research from the Sleep Research Society dating back to the late 1990s shows that sleep problems increase during perimenopause, even in women without significant night sweats.

Mood Changes

Perimenopause can significantly affect your emotional wellbeing. Learn more in our guide to perimenopause anxiety and mood changes. The Penn Ovarian Aging Study (1996-2012) and SWAN study found that women are 2 to 4 times more likely to experience depression during perimenopause, even without prior history.

Other Common Symptoms

Research documents these additional perimenopause symptoms:

Brain fog and memory changes
Vaginal dryness
Decreased libido
Joint aches
Weight gain (especially around the midsection)
Headache changes
Breast tenderness

How to Know When Perimenopause Is Ending

Perimenopause ends when you reach menopause, defined as 12 consecutive months without a period.

Signs that perimenopause may be nearing its end:

Longer gaps between periods (more than 60 days)
Lighter periods when they do occur
Symptom changes: For some women, hot flashes peak then decrease; for others, they continue or worsen
FSH levels consistently elevated (though testing still has limitations)

Research from multiple longitudinal studies found that the average woman has her final period around age 51, but the range is 45 to 55 years.

A Practical Approach to Diagnosis

Given the limitations of testing, most healthcare providers use a clinical approach:

Step 1: Age and Symptoms If you are over 40 (or over 45) and experiencing characteristic symptoms, perimenopause is the likely explanation.

Step 2: Rule Out Other Causes Your provider may test for:

Thyroid dysfunction
Pregnancy (if applicable)
Other hormone disorders

Step 3: Track Your Patterns Keeping records of your cycles and symptoms provides valuable diagnostic information.

What to Track

The most useful information for your healthcare provider includes:

Menstrual Tracking

First day of each period
Length of bleeding
Flow (heavy, medium, light)
Any spotting between periods

Symptom Tracking

Hot flashes and night sweats (frequency and severity)
Sleep quality
Mood changes
Energy levels
Any other symptoms

Context

Stress levels
Treatments you are trying
Other factors that might affect symptoms

When to See Your Doctor

Consider scheduling an appointment if:

You are under 40 with perimenopause symptoms (possible premature ovarian insufficiency)
Your symptoms significantly impact quality of life
You have very heavy bleeding or bleeding after sex
You want to discuss treatment options
You are uncertain whether your symptoms are perimenopause-related

The Bottom Line

Diagnosing perimenopause is primarily based on age, symptoms, and menstrual patterns rather than blood tests. While this can feel frustrating when you want a definitive answer, the good news is that treatment decisions are based on your symptoms rather than lab values.

If you are experiencing changes that suggest perimenopause, tracking your symptoms and working with a knowledgeable healthcare provider can help you navigate this transition and access effective treatments when needed.

Remember that perimenopause is a normal life stage, not a disease. Understanding what is happening in your body empowers you to seek appropriate support and make informed decisions about your health.