The perimenopause stage can begin an earlier at the mid to late 40s. During this period, the ovaries start to gradually produce less estrogen. During this transition, women can still be on a regular menstrual cycle and can become pregnant but they may start experiencing menopausal symptoms. Perimenopause stage will stop when the ovaries completely cease to release eggs and the menopause begins. There are symptoms associated with menopause that can be experienced during perimenopause. Although women may experience different symptoms, the common cause is usually decreasing estrogen levels. Since estrogen is used by most body parts for various functions, as the levels fluctuate, different systems will be affected.