Perimenopause explained: everything you need to know about the stage before menopause 

While menopause is increasingly recognized in healthcare and public conversation, perimenopause remains less understood and underdiagnosed. Although it has always existed, formal research, clinical training and public literacy on the topic are relatively recent, even compared to menopause. New global studies and updated guidelines have emerged mainly in the last 5–7 years, with momentum accelerating since 2023.  

According to Medcan’s Clinical Director of Women’s Health, Menopause Certified Physician, Dr. Zelovitzky, there is still a major gap in solutions and lack of education for the medical professionals on the topic of perimenopause. In large part, this is due to a Women's Health Initiative study that came out in 2002 suggesting hormone therapy caused breast cancer, which was later proven inaccurate. 

“At the time of that study, education and research stopped, which meant doctors – like me – were lucky if we had even one day of menopause education in medical school,” said Dr. Zelovitzky. “I didn’t even hear the word perimenopause until I was well past my medical education. This lack of focus on education means that most physicians haven’t had the training.” 

In Canada, the average age of natural menopause is 51. Perimenopause, which is the transition leading up to menopause, begins much earlier – in the early 40s and sometimes in the late thirties – and can last four to eight years or longer. As a result, many women experience menopausal symptoms for years before they are in menopause. 

Research also suggests that perimenopause may now start earlier for many women. In part, this may reflect improved awareness. Women today are better able to name symptoms and seek help sooner. As many as 90% of women may seek medical care for symptoms in perimenopause.  

The timing of perimenopause means women are navigating this transition while balancing careers, caregiving and relationships, often without adequate information or support. During perimenopause, fluctuating hormones can affect energy, concentration, mood and digestive health; symptoms that can negatively impact work performance and relationships. Women may also start to notice changes to their skin, hair loss or experience musculoskeletal pain.  

And when many women do seek support for their symptoms, perimenopause is often overlooked as an underlying cause. One large US study published in npj Women’s Health (2025) reports that many women seek care for mood, sleep, cognitive, or fatigue symptoms years before being recognized as perimenopausal, noting a "distinct lack of research and awareness” contributing to misdiagnosis. 

At Medcan, perimenopause and menopause education is a core part of our Menopause and Perimenopause Program. Drawing on insights from Dr. Jennifer Zelovitzky, this guide explores what perimenopause really is, why it shouldn’t be overlooked and how evidence‑based, specialized care can help you regain balance and feel more like yourself. Here, you’ll learn what to expect, how to manage symptoms, and how to advocate for the support you deserve. 

What is perimenopause? 

Perimenopause is the transitional stage leading up to menopause when the body gradually goes through changes related to hormone production. It most often starts in the early to mid‑40s, though for some women it can begin in the late 30s.  

Over the course of a woman’s life, the number of eggs a woman has in her ovaries decline due to normal ovarian aging. Eggs start declining at birth and by perimenopause women reach a threshold where there are not enough estrogen producing eggs to keep the estrogen receptors “happy.”

Women are born with their lifetime supply of eggs – about 1–2 million. These are shed over a woman’s life due to ovulation – when an ovary releases an egg, making it able to be fertilized by sperm – and a process known as follicular atresia where follicles, which nourish immature eggs, degenerate.  

While atresia is constant throughout a woman’s life, it accelerates in the 10 years preceding menopause, leading to a critical threshold where not enough follicles remain for regular menstrual cycles. As this happens, the ovaries no longer release hormones like estrogen and progesterone in a steady, predictable way. Instead, hormone levels fluctuate. The loss of estrogen can affect energy, concentration, mood, sleep, digestion, skin, hair and musculoskeletal health. In perimenopause, with estrogen rising and falling unevenly, hormonal swings are also common. 

Progesterone levels often decrease as well. Progesterone helps balance estrogen and supports regular menstrual cycles and sleep. During perimenopause, ovulation becomes less frequent. When ovulation does not occur, progesterone is not produced. This can contribute to heavy or irregular periods, increased anxiety and sleep disturbances. 

These hormonal changes also affect communication between the ovaries and the brain. Hormonal changes impact the hypothalamus – a brain region that regulates body temperature, sleep and mood. When hormone signals become inconsistent, the brain receives mixed messages. This can trigger symptoms such as hot flashes. 

During perimenopause, menstrual periods do not stop altogether, but they often become irregular. At the same time, common symptoms include: 

• Trouble sleeping 
• Mood changes, anxiety, or low mood 
• Brain fog or memory difficulties 
• Joint aches and stiffness 
• Vaginal dryness 
• Fatigue 

Current research suggests that there are approximately 34 to 40 symptoms associated with the menopause transition. They include less common issues such as burning mouth – a feeling of burning, tenderness, tingling, heat, or numbing in or around the mouth. 

Perimenopause officially ends when menopause begins, which is medically defined as having no menstrual periods for 12 consecutive months. But during this transition, unmanaged symptoms can affect quality of life. This is why, today, perimenopause is increasingly recognized as a significant public health and workplace issue, not a niche or isolated concern. 

What are the first signs and symptoms of perimenopause? 

Perimenopause is often misunderstood because menstrual periods may still appear regular when other symptoms begin. Symptoms may also fluctuate, improving and worsening over time, which can make it difficult for them to be attributed to a single cause.  

To make diagnosis more complicated, perimenopause is also not defined by one symptom or a sudden change. It is a gradual transition driven by fluctuating hormone levels that affect the entire body. Many symptoms of perimenopause can also be attributed to other health concerns and are part of why they are often overlooked. The most common symptoms women experience include: 

• Menstrual cycle changes: Periods may become less predictable, arriving earlier or later than expected, becoming heavier or lighter, or occasionally being skipped. 
• Premenstrual symptom changes: Changes to premenstrual symptoms can also signal the start of perimenopause. Some women experience worsening PMS, including breast tenderness, bloating, cramps, headaches, or mood swings. 
• Sleep disruption: Difficulty falling asleep, waking during the night or feeling unrefreshed despite adequate sleep can occur in the early stages of perimenopause.  
• Mood changes: Many women notice changes in mood early in perimenopause, including increased irritability, heightened anxiety or greater emotional sensitivity. 
• Brain fog Cognitive symptoms – commonly described as brain fog – may emerge since estrogen plays a key role in memory, attention, and verbal fluency. Trouble focusing, forgetting words or names or feeling mentally less sharp are common experiences.  
• Low energy: Persistent fatigue or reduced resilience to daily demands is common and may be driven by poor sleep, hormone fluctuations, or both.  

In some cases, women in perimenopause may experience hot flashes or night sweats, although for many, these symptoms tend to appear later. 

How is perimenopause diagnosed? 

Perimenopause is identified through a clinical assessment. A physician will look at the overall pattern of changes you may be experiencing, including: 

• Changes in menstrual timing, flow, or regularity 
• Symptoms such as sleep disruption, hot flashes, mood changes, brain fog, or worsening premenstrual symptoms 
• Age, as perimenopause most commonly begins in the 40s, though it can start earlier for some women 

When these factors occur together, and particularly when symptoms evolve or persist over time, and other potential conditions are ruled out, this is when perimenopause is often identified and can be diagnosed with confidence. 

Why blood tests are often unreliable 

Hormone blood tests are generally not recommended to diagnose perimenopause. During the transition, hormone levels fluctuate widely. As a result, test results may appear normal one day and abnormal the next. Therefore, they can be misleading. 

In certain situations, health providers may order blood tests but these may be used to rule out other conditions – such as thyroid disease, anemia, or vitamin deficiencies – to evaluate possible early or premature menopause (before age 45 or 40), or to investigate symptoms that are severe, unusual, or occurring at a younger age. 

In these cases, repeat hormone testing or additional investigations may be appropriate. In most situations, however, clinicians rely on a person’s symptoms, menstrual changes, and age. 

As Dr. Zelovitzky explains: “Unfortunately, I’ve seen patients being dismissed because hormonal bloodwork results are normal. When this happens, women are often left without support or solutions, being told ‘there’s nothing we can do.’ However, bloodwork is often normal for women who are still in their reproductive years, so going by these tests is unreliable.” 

Treatment options and lifestyle strategies that improve perimenopause symptoms 

Perimenopause is highly individual with each woman experiencing different symptoms and needing different approaches to care. Treatment may include medication, when appropriate, with lifestyle strategies as a first and critical line of support.  

"Unfortunately, patients get dismissed because hormonal bloodwork results are normal. However, they are often normal for women who are still in their reproductive years, so that's unreliable.”

- Dr. Jennifer Zelovitzky, Medcan's Clinical Director of Women's Health