Throughout life, women experience many life-changing stages that are either learned about through experience or from knowledge shared by other women (or people) in your life. Menopause is one of those stages that either hits you like a ton of bricks or eases in like a new pair of shoes.

Here’s five things about menopause that will either surprise you or confirm what you’ve been experiencing.

1.  Most women experience menopause between the ages of 45 and 55 as a natural part of biological aging. The average age is 51 in the U.S.

2.  There are 3 phases of menopause: Perimenopause, Menopause and Post-menopause. Perimenopause is the time before menopause when the ovaries gradually stop working. You are officially in menopause when you have not had a menstrual cycle for 12 months. Post-menopause marks the end of the reproductive stage of a woman’s life.

3.  During Perimenopause, women can start experiencing the many symptoms of menopause, including:  irregular periods, mood swings, irritability, fatigue, adult acne, difficulty sleeping, weight gain, vaginal dryness, discomfort during sex, night sweats and hot flashes, to name a few. Symptoms and the severity experienced vary from woman to woman.

4.  The two most common symptoms or complaints about menopause are hot flashes and vaginal dryness. Both occur due to decreased estrogen levels. Research suggests that dropping estrogen can change how the brain perceives temperature, causing fluctuations in body temperature or hot flashes and night sweats. While other menopausal symptoms, such as hot flashes, typically decline over time, vaginal dryness tends to linger because it results from physical changes in the vagina due to estrogen loss.

5.  The menopause transition, from peri to post, lasts about 7 years on average, yet can last as long as 14 years depending on lifestyle factors and ethnicity.