Premenopause - This is the stage before women enter the menopause transition. At this point, women shouldn't be experiencing symptoms, and the menstrual cycle should be consistent and regular. Women in this stage are medically considered to be in their reproductive years.

Perimenopause - As women move toward their 40s, estrogen, progesterone, and testosterone begin to fluctuate and decline. The primary indicator of perimenopause is when periods become irregular - heavier/lighter, more spaced out, etc. Women may also start to notice physical, mental, and emotional symptoms like hot flashes, mood swings, and fatigue. On average, perimenopause lasts for 7-10 years.

Menopause - Menopause is defined as the threshold at which a woman has gone 12 consecutive months without a period. The same symptoms my persist, worsen, or improve, and new symptoms may develop.

Postmenopause - This stage describes the years that follow, once a woman has crossed the menopause threshold. At this point, symptoms may change, ease, or cease entirely. A woman spends the rest of her life in postmenopause.