A comprehensive international study found pregnancy can delay the onset of multiple sclerosis by more than three years. In the study, researchers suggest pregnancy could reduce the abnormal over-activity of the immune system that causes MS, potentially long-term.

The study into MS and pregnancy, from the Monash University Department of Neuroscience, in Melbourne, Australia, looked at whether pregnancy can delay the onset of MS. The researchers studied more than 3,600 women attending four MS clinics in two countries (Czech Republic, and Australia), all of whom were enrolled in MSBase.

The study found women who have been pregnant were diagnosed with their first MS symptoms, on average, 3.3 years later, compared to women who had never been pregnant. A similar delay in MS onset was also observed in women who had carried a baby to term – with onset delayed, on average, by 3.4 years. 

The MSBase Registry has been following patients over time in 35 countries with MS since 2001, and became an Australian not-for-profit foundation in 2004. It is managed by the chair of the Multiple Sclerosis and Neuroimmunology research group at Monash University's Department of Neuroscience.

The findings were published in the Journal of the American Medicine Association Neurology.