Between puberty and menopause, a woman's ovaries play critical roles, enabling her to bear children and helping maintain many body systems. The ovaries do this by producing an egg each month and by producing rhythmic releases of hormones - androgens, progestins and estrogens. As menopause begins, hormone production declines. As fewer eggs are released, pregnancy becomes less likely. Eggs that do become fertilized are more likely to have damaged chromosomes, which can cause birth defects.
Miscarriages become more common.
As hormone levels decrease over time, menstrual flows may become lighter, heavier or irregular. Estrogen decline at menopause can have a number of effects, including insomnia, fatigue, memory loss, flushing and hot flashes, irritability and mood swings. The vagina may shorten, and its walls become thin and dry. The alkaline balance of the vagina may change, allowing bacterial infections to occur. Burning may accompany urination.