A study in the medical journal Archives of Neurology has found that the risk of developing multiple sclerosis was reduced in women taking oral contraceptives.
Previous studies had shown that estrogen delayed the onset and eased the course of a multiple sclerosis-like disease in animals, suggesting to researchers that oral contraceptives, which contain estrogen, may alter the risk of developing the disease.
The study, conducted by the Harvard School of Public Health, ran over a three-year period and found that hormone levels - affected by either oral contraceptives or pregnancy - did indeed influence the onset of multiple sclerosis. "The incidence of multiple sclerosis in oral contraceptive users was 40 percent lower than in nonusers," the study authors said.
"Our findings suggest that high levels of exogenous [from outside the body] estrogens from oral contraceptive use and of endogenous [from the body] estrogens during pregnancy may delay the first clinical attack of MS. Recent oral contraceptive use and, possibly, current pregnancy are associated with a lower risk of developing multiple sclerosis," the researchers said.
Interestingly, the researchers warned that the period after pregnancy was when multiple sclerosis had a higher probability of occurring. "Women had a higher risk of developing first symptoms of multiple sclerosis in the six months following a pregnancy and a non-significant lower risk during pregnancy... This is consistent with studies on the effect of pregnancy in patients with multiple sclerosis and the immunological changes associated with pregnancy," they concluded.