The clitoris is made up of spongy erectile tissue that fills with blood during sexual arousal. This spongy tissue is maintained by the hormone testosterone and is dependent on good blood flow. When a woman's level of testosterone drops significantly, such as with menopause or the use of hormonal birth control, she could experience a decrease in size, function, and sensitivity of the clitoris over time, also known as clitoral atrophy.
All the tissues of the body depend on good blood flow for their nurishment and functioning. Because of this, having regular sexual activity or some form of clitoral stimulation along with arousal will continue to provide those tissues with the blood they need. Engaging in regular exercise helps by both increasing general blood flow as well as by increasing and maintaining the production of testosterone. Some women also may benefit from having their testosterone supplemented after menopause in order to prevent clitoral atrophy.