Women taking oral contraceptives for 3 years saw a reduction in the odds of developing multiple sclerosis (MS). The study, as reported in the Archives of Neurology (September 2005), compared 106 women newly diagnosed with MS between January 1, 1993, and December 31, 2000, with 1001 women without the disease. The participants were chosen for the study based on a research database that included medical and pharmacy records for 3 million British patients.
"The incidence of MS in [oral contraceptive] users was 40% lower than in nonusers," the investigators reported. "Women had a higher risk of developing first symptoms of MS in the 6 months following a pregnancy and a nonsignificant lower risk during pregnancy, compared with those with no pregnancy.... This is consistent with studies on the effect of pregnancy in patients with MS and the immunological changes associated with pregnancy."