Study Disputes Pregnancy Link to MS Relapses

THURSDAY, March 7, 2019 (HealthDay News) -- A new study challenges the long-held belief that multiple sclerosis (MS) can flare up right after pregnancy in women with the relapsing-remitting form of the disease.

In that type of MS, symptoms arise, then go into periods of remission.

"These results are exciting, as MS is more common among women of childbearing age than in any other group," explained study author Dr. Annette Langer-Gould, from Kaiser Permanente Southern California.

"This shows us that women with MS today can have children, breastfeed and resume their treatment without experiencing an increased risk of relapses during the postpartum period," Langer-Gould said in an American Academy of Neurology news release.

The theory that women have an increased risk of relapse is more than 20 years old, so the researchers wanted to determine if it was actually true.

They reviewed data from California on 466 pregnancies among 375 women with MS from 2008 to 2016. Thirty-eight percent of the women did not receive any treatment for MS in the year before they became pregnant.

At the start of pregnancy, 15 percent of the women had clinically isolated syndrome -- the first episode of MS symptoms. Eight percent of the women had an MS relapse during pregnancy.

In the year after giving birth, 26 percent of the women had a relapse, 87 percent breastfed, 35 percent breastfed exclusively and 41 percent started taking their MS treatments again.

The annual relapse rate for the women was 0.39 before pregnancy, 0.07 to 0.14 during pregnancy, and 0.27 in the first three months after birth. The rate returned to pre-pregnancy levels at 0.37 four to six months after birth.

Women who breastfed exclusively for at least two months were about 40 percent less likely to have a relapse than women who did not breastfeed. Women who breastfed and also used formula for two months were just as likely to have a relapse as those who did not breastfeed.

Of the women who breastfed exclusively, 46 out of 167 resumed using MS treatments while breastfeeding. Interferon-betas and glatiramer acetate were the most commonly used medications. Resuming the use of these treatments did not impact the risk of relapse.

The study is scheduled to be presented at the American Academy of Neurology's annual meeting in Philadelphia, held May 4-10. Such research is considered preliminary until published in a peer-reviewed journal.

More information

The National Multiple Sclerosis Society has more on MS and pregnancy.