Does Pregnancy Delay Multiple Sclerosis Onset?

Past studies suggested that pregnancy has a protective effect and accumulative effect on the development of multiple sclerosis (MS), possibly through the anti-inflammatory effects of hormones. Investigators for this retrospective cohort study included 2557 women diagnosed with MS from four hospitals.

Before MS onset, 46% of the women had been pregnant and 43% had given birth. Women with prior pregnancies had a later onset of first MS symptoms than women who had never been pregnant (hazard ratio, 0.68; 95% confidence interval, 0.62-0.75). Pregnancy resulted in a median delay of 3.3 years to first MS symptoms. Additional pregnancies did not add to this effect.