By Madeleine Castellanos, M.D.
There are many reasons why women experience a loss of sexual desire. One of the most common, and least acknowledged, is the use of hormonal birth control. Most birth control pills and other hormonal birth control methods use some form of estrogen. The effect this has in the body is to increase the body's production of Sex Hormone Binding Globulin (SHBG), a protein that transports hormones around the body in the bloodstream. The trouble is that while hormones are bound to SHBG, they can't be used by the tissues. The hormone that has the highest rate of binding to SHBG is testosterone. So when a woman uses hormonal birth control containing estrogen, she is effectively decreasing her levels of available testosterone. Since testosterone helps fuel sexual desire, fantasy and also lubrication in response to arousal, many women are left feeling very blase about sex. Oftentimes, it is not an issue for women in their late teens or early twenties. But as their hormone levels start to decrease naturally with age, it can become a very surprising reality.
A similar phenomenon occurs during menopause, either natural or surgical-induced because of removal of the ovaries. The onset of low sexual desire is usual less noticeable with naturally-occurring menopause because of the gradual decline in hormone levels as opposed to the abrupt plummeting of hormones after surgery. Since a woman's ovaries produce about half of her overall testosterone, once they are no longer there, or no longer receiving the message from the brain to make sex hormones as in natural menopause, her desire seems to also crawl back into its shell. Interestingly enough, a woman's level of desire can be fairly well-preserved depending on her psychology and her level of sexual activity.
Studies show that women who had a satisfying sex life before menopause tend to have greater sexual functioning and sexual satisfaction after menopause as well. Remember that a woman's arousal is fueled not only by good physical stimulation, but also by an inviting emotional environment. It's difficult to say which is more important, a woman's attitude towards sex and enjoyment in her sex life overall, or having good blood flow with regular sexual activity. Those women who continue to have regular penetrative sex (at least once a week either with intercourse or in masturbation with a dildo or vibrator) end up having better blood flow to all of the tissues of her sex organs.
Obviously, lifestyle and the satisfaction with your relationship also contribute greatly to a woman's level of sexual desire. Being out of shape, being exhausted, or carrying pent up anger or resentment all tend to squash the life out of any sexual desire that was there before. But there are solutions. It's never easy to make the lifestyle changes that lead you back to balance, but the payoff is great. Similarly, if you suspect that you may be having hormonal causes or other physical causes keeping you from desiring sex, such as pain or discomfort, please speak to your gynecologist about it.