What term is used to designate the transition phase between regular menstrual periods and no periods?

The transition phase between regular menstrual periods and no periods is known as perimenopause. It typically occurs in women between the ages of 45 and 55 and can last for several years. During this time, women may experience irregular periods, hot flashes, night sweats, mood swings, and vaginal dryness. Perimenopause is a natural part of aging and does not require treatment, but some women may choose to take hormone replacement therapy to relieve symptoms.