Are Oral Contraceptives a Risk Factor for Multiple Sclerosis?
Two studies, one new and one conducted previously, suggest that oral contraceptives are a risk factor for multiple sclerosis. How concerned should you be if you are a woman of childbearing age?
The findings of the two studies indicate that women who use oral contraceptives that contain norethindrone or levonorgestrel have an increased risk of developing multiple sclerosis when compared with women who do not use these birth control pills. Both norethindrone and levonorgestrel are progestins, which are synthetic versions of the natural hormone progesterone.
The more recent study involved about 4,300 women whose data was evaluated for the period from 2008 to 2011. Here is what the authors found:
- Of the women who took an oral contraceptive that contained norethindrone, there was a 57 percent increased risk of multiple sclerosis or clinically isolated syndrome when compared with women who had not taken oral contraceptives.
- Among women who had taken oral contraceptives that contained levonorgestrel, the risk of multiple sclerosis was similar.
- Women who had taken an oral contraceptive that contained the progestin called drospirenone did not show an increased risk of multiple sclerosis
The investigators allowed for other factors such as smoking, body mass index, parity and miscarriages. However, they did not account for diet, vitamin D levels, or other lifestyle issues that may have an impact on development of the disease.
One factor that may be instrumental in explaining why these progestins seem to be associated with an increased risk of multiple sclerosis is that they both have androgenic effects. Androgens are hormones that are instrumental in male traits and reproductive activities.
In women, one of the main functions of androgens is to convert to estrogens. Androgenic effects can include the appearance of acne or facial hair, hair loss, and oily skin. Drospirenone, however, does not trigger androgenic effects.
The earlier study, which also was conducted by Kaiser Permanente, involved 305 women who had multiple sclerosis or clinically isolated syndrome and 3,050 disease-free women. When the investigators evaluated the use of oral contraceptives by the women, they found the following:
- 29 percent of the women with multiple sclerosis and 24 percent of those who were disease-free had used oral contraceptives for at least three months
- Most of the oral contraceptives used contained both estrogen and progestin
- Women who had used oral contraceptives were 35 percent more likely to be diagnosed with multiple sclerosis than women who had not used the hormones
The findings of these two research efforts indicate that the use of oral contraceptives—especially those that contain androgen-active progestins—may increase a woman’s risk of developing multiple sclerosis. How much weight this potential risk factor has in determining the development of MS is not known, but it is one to consider, especially among women who may have other risk factors for multiple sclerosis.
American Academy of Neurology
Hellwig K et al. Progestin content of oral contraceptives and the risk of multiple sclerosis. ACTRIMS-ECTRIMS 2014; Abstract P856