Taking contraceptive pills can increase a woman's odds of developing multiple sclerosis (MS), a disease that affects the brain and spinal cord leading to problems in balance, vision and movement.
In a new study which will be presented at the 66th annual meeting of the American Academy of Neurology in Philadelphia April 26 to May 3, researchers analyzed the health records of more than 300 women who were diagnosed with MS or its precursor known as clinically isolated syndrome (CIS). They also gathered information on the women's birth control use and then compared their records to over 3,000 women who did not have MS.
The researchers found that among women who developed MS, 29 percent had used birth control pills for at least three months within the three years before their symptoms began. Meanwhile, only 24 percent of those who did not have the disease used oral contraceptives. The researchers also found that women who had used birth control pills were 35 percent more at risk of developing MS than women who did not take them.
"These findings suggest that using hormonal contraceptives may be contributing at least in part to the rise in the rate of MS among women," said study author Kerstin Hellwig, a post-doctoral research fellow with Kaiser Permanente Southern California.
Although the researchers found an association between use of birth control pills and multiple sclerosis, they cautioned that their study does not establish a cause and effect relationship. "These results are demonstrating an association. I don't want to say that we can firmly establish causality," Hellwig said
Hellwig also pointed out that if birth control pills do have a role in MS, it is probably the effect of hormones on the body's immune system. Most of the women involved in the study had been using a combination of estrogen and progestin.
"At this point, women who take oral contraceptives shouldn't be concerned about developing MS because of oral contraceptives. It may be one of many factors, but it's not the one factor causing MS," Hellwig said.
The researchers also said that while the study's finding shows a link between contraceptive pills and MS, it does not mean that women should stop using birth control.
"We say the use of birth control might explain a little bit of the increasing incidence [of MS] among women, but only to a small amount... [We] don't intend to mean that young women should avoid birth control to avoid MS," Hellwig said.