A study published in January, 2006 in the Journal of Sexual Medicine claims that women who use birth control pills may suffer from long term side effects. Possible side effects include decreased desire and arousal, decreased lubrication, and increased sex-related pain.

Researchers studied a group of 124 women, all of whom had previously suffered from some degree of sexual dysfunction. 69 of the women continued using the pill, 39 were discontinued users, and 23 had never used it.

The research team analysed blood samples taken from women who had discontinued use of the pill six months earlier, and found that they had significantly less available testosterone. This would make them more prone to suffer from side effects such as decreased sexual desire and less frequent arousal.

Increased globulin levels means less testosterone

According to study leader Dr. Claudia Panzer of Boston University, the women who were currently taking the pill had as much as four times the level of testosterone-binding globulin in their blood as those not taking the pill. This is what reduces the amount of testosterone the body has at its disposal.

But the study found that after six months of not taking the pill, globulin levels were still roughly twice as high in those who had taken the pill, compared to those who had not. And eleven women who were tested after more than 11 months still reported having almost twice the globulin level as the group that had not taken the pill.

These observations were surprising, the authors said, "as the effect of oral contraceptives on sex hormone-binding globulin levels should have subsided." The findings are even more interesting, the study noted, because these women also received transdermal testosterone therapy, which should have decreased sex hormone-binding globulin levels.

All patients were offered a transdermal testosterone gel to improve their sexual function, but even with this therapy globulin levels were much higher than in those who had not taken the pill.

The report noted that earlier research has shown that increases in sex hormone-binding globulin levels from using birth control pills result in a 40% to 60% decrease in free testosterone levels.

Long term impact

The researchers speculated that the synthetic estrogens in oral contraceptives may trigger more permanent changes in the way the genes function, leading to much longer lasting reductions in the amounts of testosterone available to the body.

So a therapy meant to enhance sexual experience may actually make it less enjoyable for many women.

The researchers were unwilling to draw hard and fast conclusions, saying only that more research is needed. The most important question left hanging is "whether sex hormone-binding globulin changes induced by oral contraceptives may or may not be completely reversible after discontinuation of oral contraceptive use and whether this leads to long-term sexual, metabolic, and mental health changes in women."

At a bare minimum, doctors should make women more aware of these possible side effects, and they should be more diligent about watching for them. They should also be less eager to opt for the easy answer, and be more open to less invasive methods of birth control such as condoms.