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Multiple Sclerosis Health Center

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Past Pregnancies May Protect Against MS

Study: Multiple Sclerosis Risk May Drop by 50% After First Pregnancy

Pregnancy and Early MS continued...

Catching women when they were first experiencing symptoms was important, Ponsonby says, because researchers were able to look at the relationship between pregnancy and MS symptoms before the disease had influenced a woman’s choice to have children.

Many young women diagnosed with MS choose not to become pregnant because of fears about whether they’ll be able to care for their children.

Previous studies had not seen an association between pregnancy and MS, perhaps because of this bias.

“This is to my knowledge the first high-quality study ... which suggests a beneficial effect of pregnancy,” Martin Daumer, PhD, scientific director of the Sylvia Lawry Centre for MS Research in Munich, Germany, says in an email. Daumer wrote an editorial on the study but was not involved in the research.

Why Pregnancy May Protect Against MS

Researchers say they aren’t sure what it is about pregnancy that may be protective, but they have some theories.

Multiple sclerosis is a disease that’s caused by immune system overactivity and irritability,” Ponsonby says. “When you’re pregnant, your body gets trained into being very, very tolerant. That’s how the immune system doesn’t reject the baby. So you get this very big training on being able to handle something that’s foreign, or not exactly ‘self,’ in the body.”

Another idea is that cells that are shed by the baby, called fetal cells, stay in mom’s body and may lead to long-term changes in the way her immune system works.

Experts say if further research confirms the findings, they may help explain the rising incidence of MS in women.

“It is possible that differences in the patterns with which people are approaching marriage, pregnancy, children, and when they have children could be affecting this change in incidence,” says Nicholas LaRocca, PhD, vice president for health care delivery and policy research at the New York City-based National Multiple Sclerosis Society, the organization that funded the research.

“If there is this protective effect of pregnancy, as the study suggests, then to some extent in industrialized countries, we’ve begun to abandon some of this protection,” LaRocca says.

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