All About the Female Reproductive System

10. Menopause

Fertility decreases slowly over time, but at a much more rapid rate between the ages of 35 to 37. Once women reach this age, their ovaries produce fewer hormones that control menstruation, estrogen, and progesterone. Menopause usually does not occur until a woman is in her 40s or 50s -- the average age for menopause onset in the U.S. is 51. A woman may experience symptoms of menopause for years before it occurs. The symptoms include vaginal dryness, night sweats, slowed metabolism, sleep disturbances, and irregular periods. Once a woman who is in the menopausal age range has gone for 12 consecutive months without a period, the physician will officially diagnose menopause.

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