The study - which looked only at women who already had sex problems - does not prove that birth control pills cause sexual dysfunction.
But it does add to previous research finding that some birth control pills can lower a woman's free-testosterone level. Women with low testosterone are prone to a number of health problems -- including sexual health.
The findings come from Claudia Panzer, MD, Irwin Goldstein, MD, and colleagues at Boston University Medical Center. Panzer is now in practice in Denver. Goldstein is editor in chief of the Journal of Sexual Medicine. The study appears in the January issue of this journal.
"We found significantly lower scores in the Full Scale [female sexual function test] and in the domain of sexual desire for women on oral contraceptives compared with those who had never used oral contraceptives," Panzer and colleagues report. "In addition … there was significantly more sexual pain in the women who were taking oral contraceptives."
Perhaps the most alarming finding - and one that needs confirmation by more rigorous studies --= is that when these women stopped taking oral contraceptives they had long-lasting increases in a protein that sucks up testosterone.
"Further research is needed to identify whether SHBG [sex hormone binding globulin] changes induced by oral contraceptives may or may not be completely reversible after discontinuation of oral contraceptives, and whether this leads to long-term sexual, metabolic, and mental-health changes in some women," Panzer and colleagues write.
Pill Hangover: Loss of Desire?
Panzer's team looked at 124 women. All had "sexual health complaints." Among these women, 62 were using birth control pills of various kinds, 39 had used the pill for at least six months but stopped at the beginning of the study, and 23 had never used the pill. The women who had never used the pill were slightly older (average age 36) than those still on the pill (average age 32) and those who stopped using the pill (average age 32).
Women who had used oral contraceptives reported greater sexual dysfunction, less sexual desire, and greater pain during sex than those who never used the pill.
Those who had used oral contraceptives had four times higher SHBG levels than those who had never used this birth control method. SHBG lasts in the body for only about two weeks. Sure enough, the women who stopped using the pill saw about a 2.5-fold drop in their SHBG levels after 106 days. But higher-than-normal SHBG levels persisted.
The researchers followed 11 of these women for a year or more. Their SHBG levels remained much higher than normal. That could be a problem, the researchers write, as women with high SHBG levels might have lower testosterone levels.
"SHBG values may remain elevated to values significantly higher than 'never users' for a prolonged period of time despite discontinuation of oral contraceptives," Panzer and colleagues warn. "This is an early observation, which needs to be evaluated further."
SOURCES: Panzer, C. Journal of Sexual Medicine, January 2006; vol 3: pp 104-113.
By Daniel J. DeNoon
Reviewed by Brunilda Nazario, MD
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