Pregnancy can delay the onset of multiple sclerosis (MS) by more than 3 years, according to a study published in JAMA Neurology

More than 2.5 million people worldwide are living with MS and women are 4 times more likely to have the disease than men. MS is also frequently diagnosed during childbearing years, according to the study. 

Study data were collected using the MSBase database, which has been used in dozens of high impact research studies on MS. The database includes more than 70,000 people in 35 countries and has been operating for more than 20 years. The study authors examined data from 3600 women in 4 MS clinics in the Czech Republic and Australia. 

According to the study results, women who had been pregnant were diagnosed with their first MS symptoms on average 3.3 years later than women who had never been pregnant. For women who had carried a baby to term, the onset delay was an average of 3.4 years. 

Although investigators do not know for sure, they believe this is due to alternations made to a woman’s DNA during pregnancy. 

"At present, we don't know exactly how pregnancy slows the development of MS, but we believe that it has to do with alterations made to a woman's DNA. We are now seeking funding opportunities to explore this exciting possibility," study leader Vilija Jokubaitis, PhD, said in a press release. 

It is also possible that pregnancy could reduce the overactivity of the immune system; however, more research is still needed, according to the study authors. 

Reference:
World's first major study into MS and pregnancy reveals it delays onset of MS symptoms by more than 3 years [News release] September 14, 2020. Melbourne, Australia. https://www.eurekalert.org/pub_releases/2020-09/mu-sim091120.php. Accessed September 25, 2020.