Menopause is a natural stage of life that marks the end of a woman's menstrual cycles, usually happening between the ages of 45 and 55. It's caused by a drop in the ovaries' production of estrogen and progesterone- two key hormones that regulate reproductive cycles and influence many systems in the body. Before menopause, there's often a stage called perimenopause (starting in the early to mid-40s) when hormone levels begin to fluctuate. This can bring on symptoms such as: •