Women whose children were born after MS began were even more likely to have a slower progression of disease than those who children were born before symptoms began, compared to childless women, the researchers found.
''Although the largest difference was found between the women who had children after the onset of MS compared to the women without children, all patients who gave birth at any point in time seemed to do better than those who did not have children," says researcher Marie D'hooghe, MD, a neurologist at the National Multiple Sclerosis Center, Melsbroek, Belgium. The study is published online in the Journal of Neurology Neurosurgery and Psychiatry.
The findings, however, shouldn't make childless women feel guilty they didn't ''help'' their disease by becoming pregnant, nor should it be a reason to attempt pregnancy, says Patricia O'Looney, PhD, vice president of biomedical research at the National Multiple Sclerosis Society, who reviewed the study for WebMD..
MS is an inflammatory disease of the central nervous system, accounting for the most frequent cause of disability in young adults. Early symptoms, which can come and go, include tingling, numbing, loss of balance, and blurred vision. As the disease progresses, loss of balance and muscle coordination can make walking difficult.
Previous research has shown that MS tends to remit during pregnancy. ''The short-term effects of pregnancy on the course of MS have been repeatedly confirmed, with a lower relapse risk during the second and especially the third trimester and an increased relapse risk in the postpartum period," D'hooghe says. "As for the long-term effects, the findings have been mixed. Most studies did not find a long-term effect of childbirth on the disease course in MS."
Evaluating Progress of MS
For the study, D'Hooghe and her colleagues evaluated 330 women with MS, with an average of 18 years with the disease, between 2005 and 2007. All women had been referred to one center in Belgium and all had experienced their first symptoms from age 22 to about 38.
Eighty of the study participants had no children, 170 had given birth before their symptoms began, 61 had given birth after symptoms developed, and 19 had given birth both before and after giving birth.
D'hooghe evaluated which women at the end of the study had disease that had progressed to the point of needing a cane, crutch, or brace to walk 100 meters (about 328 feet). This category of disability is called Expanded Disability Status Scale or EDSS 6.
Childbirth affected the speed of progression of MS, the researchers found. After an average of 18 years, 55% had reached EDSS 6. Among the findings:
- Women who had given birth to one or more children at any point -- before or after symptoms began -- were 34% less likely than childless women to progress to EDSS 6.
- Women whose children were born after symptoms began were 39% less likely to progress to EDSS 6 than childless women -- even taking into account the age at which symptoms began.
''These results are encouraging but do not mean that women with MS who have children are free from progression of disease," D'hooghe writes in an email interview with WebMD.
Women who did not have children after symptoms began progressed to the EDSS 6 category in about 13 to 15 years, while those who did have children after onset of symptoms took 22 or 23 years to reach EDSS 6.
When the researchers looked at those whose disease began before age 30 -- to rule out effects due to age -- they found that the average age of progression to EDSS 6 was 37 among the childless, but 43 among those who gave birth after the diagnosis.
Exactly why pregnancy seems to slow disease progression isn't known, but it could be that sex hormones secreted during pregnancy may change the body's immune response and slow down damage.
''Hormonal effects might play a role," D'hooghe says.
The new research "ought to relieve at least some of the concerns of patients about how they are going to do with their disease [after pregnancy]," says Maria Houtchens, MD, a neurologist at Partners Multiple Sclerosis Center at Brigham & Women's Hospital and an instructor of neurology at Harvard Medical School, Boston, who has published on the topic.
Even so, she says, "there are still some women with MS who need to be cautious about pregnancy." Among those are women with aggressive disease or frequent relapses, she says.
Another consideration, she adds, is that the standard of care is not to take MS drugs during pregnancy. "I would caution people not to jump into pregnancy. Every patient is different."
One strength of the study, says O'Looney, is the length of the follow-up.
But, she adds, ''there might be something else at play here'' in addition to pregnancy affecting disease progression. ''Some women with severe disease may have chosen not to have children."
''The most important thing here for consumers is, we don't want any woman who has MS to feel guilty one way or the other. We don't want someone to read into this and say, 'Oh did I make my MS worse by not having children?'"