Defining Premenopause, Perimenopause, and Menopause

Women experience a wide range of fluctuations in hormones during various life stages that influence fertility. As a young adolescent, for example, hormones will influence when she is able to reproduce—by initiation of the first menstrual cycle (monthly period). Around her mid-20s, a woman's fertility peaks, after which it starts to gradually decline. As a woman ages, she will eventually no longer be able to conceive a child.

The period when a female is no longer fertile is commonly known as menopause. However, there are various phases between adolescence and menopause. This can be confusing, partially because the terms describing the stages of a woman’s fertility cycle can vary. 

Two such terms are premenopause and perimenopause. These two terms, which define phases of menopause, are often mistakenly interchanged.

Menopause usually occurs between the ages of 45 and 55, but for some women, menopause can happen as early as the 30s or 40s. For other women, menopause may not occur until they reach age 60, but the average age for a woman to be in menopause, according to The Global Library of Women’s Medicine, is age 51. 

Medically, a woman is considered in menopause when 12 consecutive months go by and she has not experienced menstruation, according to Cleveland Clinic. It’s important to note that other glands in the body will continue to make estrogen (and other sex hormones). However, the level of sex hormones produced in the body after the ovaries stop making estrogen will be significantly lower.

Under normal circumstances, a woman does not suddenly experience menopause. Instead, it occurs gradually and involves different phases.

Perimenopause usually occurs during the 40s. The most significant sign that a woman is in the perimenopausal phase of her reproductive cycle is that she has visible symptoms that occur due to the decrease in estrogen and other sex hormones. Some healthcare providers may refer to this phase "menopause transition." Common signs and symptoms of perimenopause may include:

• irregular and/or abnormal periods (that may be heavier or lighter in flow)
• hot flashes
• night sweats
• breast tenderness
• increase in weight gain
• worsening symptoms of PMS (before periods begin)
• thinning of hair
• lower sex drive (or loss of sex drive)
• vaginal dryness
• headaches and/or muscle aches
• problems concentrating
• memory problems
• mood swings
• tachycardia (an increase in heart rate)
• an increased incidence of urinary tract infections (due to hormonal changes that cause thinning of the urethra)
• problems conceiving (in women trying to have a baby)

Note, the symptoms of perimenopause are the same after menopause, but they begin to worsen as a woman gets closer to menopause.  Perimenopause usually occurs over an eight to 10-year time span, with estrogen gradually decreasing over time. 

Once a woman reaches full menopause, she may or may not continue to have physical and/or emotional symptoms (such as hot flashes and mood swings). It’s also important to note that during perimenopause a woman can still get pregnant, but it will probably be more difficult than when she was younger.

This phase does not involve any of the classic signs or symptoms of menopause (such as night sweats, insomnia, or missed periods). A person experiencing premenopause has periods that may or may not be regular, and she is still considered fertile or in her reproductive phase of life. 

Theoretically speaking, a woman is considered in the premenopause phase any time before she enters menopause.

Early Menopause

In some instances, a woman can experience menopause earlier than her 40s, perhaps even before her 30s. Although the age that a woman begins her menses has nothing to do with when she will enter the perimenopausal phase of her fertility cycle, perimenopause and menopause can be influenced by several factors, including:

• Smoking
• Genetics (maternal history of early menopause)
• Chromosome defects
• Autoimmune diseases
• Hysterectomy (removal of the ovaries)
• Chemotherapy (or other cancer treatments)

Amenorrhea simply means the absence of monthly periods. It is commonly mistaken for early menopause. Any time a woman stops having monthly periods, it’s important to consult with the healthcare provider for a medical evaluation to discover the underlying cause.

There are several reasons that amenorrhea may occur when it is not linked with menopause or perimenopause. In this scenario, the woman is still considered to be in the premenopausal phase of her fertility cycle. There are several reasons that amenorrhea can occur, including:

• thyroid problems
• suddenly stopping birth control
• ovulation cessation (most commonly cause by pregnancy, other causes include sudden weight loss, over exercise, nutritional deficits involving weight loss, eating disorders, and more)
• severe stress
• obesity (being overweight)
• other medical conditions (such as pituitary tumors, polycystic ovary syndrome and more)
• premature ovarian failure (POF) a condition that may involve some of the same symptoms of perimenopause, such as hot flashes, but it occurs due to an unknown cause

According to Dr. Andrew Weil, M.D., it’s estimated that 250,000 women under age 40 are affected by POF. This condition causes the ovaries to simply stop functioning during a time in a woman’s fertility cycle when the ovaries are normally producing estrogen and she is fertile. Treatment of POF involves hormone replacement therapy (HRT). 

A Word From Verywell

There are many terms that describe the phases of a woman’s reproductive cycle. Knowing the difference between the various phases of fertility is important for many reasons. In short, terms that describe menopause provide a timeline that occurs from the first menstrual period—when a woman can conceive—to the time when estrogen is no longer being produced by the ovaries and ovulation has come to a halt, called menopause.