Oral contraceptives linked to increased risk of multiple sclerosis

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In a new study, researchers found an increased risk of multiple sclerosis (MS) among women who have taken oral contraceptives. However, the findings do not mean women should stop using birth control, the researchers say.

Utilizing membership data from Kaiser Permanente Southern California, researchers analyzed the health records of 305 women aged 14 to 48 who were diagnosed with MS or its precursor, clinically isolated syndrome (CIS), between 2008 and 2011.  They looked at the women’s birth control use up to three years prior to the onset of MS symptoms

Overall, researchers found a 30 percent increased risk of developing MS amongst women who had at least three months of oral contraceptive use, compared to a control group of 3,050 women who did not have MS. They found that 29.2 percent of women with MS used birth control before their diagnoses, while 23 percent of women in the healthy control group used birth control– showing an increased risk with higher use of the drug, study author Dr. Kerstin Hellwig, a post-doctoral research fellow at Kaiser Permanente Southern California, told FoxNews.com.

Additionally, for women who did not currently use an oral contraceptive but had in some time in the three years prior to being diagnosed, there was also a slightly higher risk.

Multiple sclerosis is an autoimmune disease affecting the central nervous system. The causes are unclear, but experts believe genetics, environmental hazards and smoking are all possible factors. The condition normally develops between ages 20 and 40, Hellwig said.

Researchers say use of birth control is not a firmly established cause for MS, but they do see a link.

“It’s not clear what role [hormones] play in the development of the disease, but it’s clear that two to three times more women than men have MS,” Hellwig said.

Hellwig noted that her team studied data for women who used oral contraceptives for at least three months, which limited the analysis because they weren’t able to study lifetime exposure. Though she expects to see an increased risk with longer use in their final analysis, which will be presented at the upcoming American Academy of Neurology’s Annual Meeting. Most of the women used an estrogen and progestin formulation of birth control, a commonly used combination.

While this preliminary analysis indicates an association, researchers cannot firmly establish causality, Hellwig warns.

“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,” she said.