With “the pill” poised to turn 50 this weekend comes new research linking hormonal contraceptives with diminished desire and other forms of “female sexual dysfunction.”

The study of more than 1,000 German female medical students found those taking birth control pills and other forms of hormonal contraception were at the highest risk for low libido and arousal problems.

The findings don’t prove cause and effect, the researchers stressed — just an association.

But birth control pills can lower circulating levels of testosterone, the “male” hormone needed to stimulate sexual desire and regulate blood flow to the genitals, in both sexes.

The study appears in the Journal of Sexual Medicine. Editor-in-chief Dr. Irwin Goldstein, a Montreal native and director of sexual medicine at the Alvarado Hospital, University of California, San Diego, said the study shows that, “when you fool around with your sex steroid hormones, you gamble with your sex life.”

“The value of this paper is to remind us that 300 million users of the pill (worldwide) are putting themselves at risk (of sexual changes), with extremely limited informed consent that this is happening,” Goldstein said.

In all, 1,086 women from six medical schools completed online questionnaires designed to identify problems with sexual function within the past four weeks. The women filled out the “Female Sexual Function Index,” a validated scale consisting of 19 questions measuring desire, arousal problems, lubrication, orgasms, satisfaction and pain.

Almost 90 per cent had used contraception, and almost all had been sexually active in the previous four weeks; 80 per cent were in a stable relationship, meaning they had the same partner for at least the past six months.

The three most common means of birth control were oral contraception (about 70 per cent), condoms (23 per cent) and the vaginal ring (seven per cent).

Based on their scores, 32 per cent of the women in the study were considered at risk for female sexual dysfunction.

Women using nonhormonal forms of birth control, such as condoms and intrauterine methods, or no contraception had higher total, desire and arousal scores than women using birth control pills, vaginal rings and other forms of hormonal birth control.

“Our data show that hormonal contraception in particular, was associated with lower desire and arousal scores when compared with other contraceptives,” the researchers write.

The group at lowest risk for female sexual dysfunction — meaning those with the highest sexual function score — were using condoms or other nonhormonal methods.

“The effect of hormones is there, we have an association. But, at this time, we cannot say if this is causality,” said Dr. Alfred Mueck, professor in the Centre of Women’s Health at the University of Tuebingen, in Germany. The study also did not look at whether different dosages or formulations make a difference.

“We can only say there might be an effect of hormonal contraceptives (on sexual functioning). But this is only one factor beside other factors that can influence sexual function.”

Women who reported higher stress also had lower desire scores. The problem “is really very multifactorial,” Mueck said.

Among the study’s other findings:

- Women in stable relationships had higher orgasm scores, but lower desire scores. The longer the partnership lasted, the more desire scores dropped.

- Smokers had a higher total sexual functioning score. “One possible explanation is that smokers might have greater ability to enjoy themselves or that the association with smoking is confounded by other factors,” the researchers write. Smokers have lower estrogen levels than non-smokers — and lower estrogen levels might result in higher free-testosterone levels. Smokers are also less likely to be on the pill. The combination increases the risk of heart attack, blood clots and stroke.

Goldstein said birth control pills inhibit the production of testosterone in the ovaries, and increase the levels of a protein that binds to testosterone, so that less testosterone is “unbound” and free to act in the body.

On May 9, 1960 the U.S. Food and Drug Administration approved the sale of oral pills for contraception for the first time.

The pill became available in Canada in 1960, but doctors could only legally prescribe it for “menstrual regulation” and other therapeutic purposes. Contraception was formally legalized in Canada in 1969.
—
Canwest News Service