MONDAY, June 8, 2009 (HealthDay News) -- New moms with multiple sclerosis who want to breast-feed but worry it might cause their disease to relapse may be reassured by a new study that discovered this is not the case for most women.
The study, in the June 8 issue of Archives of Neurology, found that almost two of three women with multiple sclerosis (MS) who breast-fed exclusively for two months or more and who were not taking MS medications did not experience a relapse of their disease while they were breast-feeding.
"The most important thing for patients and physicians to know is that there's no evidence that breast-feeding is harmful for women with MS," said study author Dr. Annette Langer-Gould, who was at Stanford University at the time of the study but is now a neurologist and research scientist with Kaiser Permanente Southern California in Pasadena.
"If mothers decide to breast-feed and do what's best for baby, we couldn't see any evidence of risk, and it may even be better for mothers to breast-feed," she said.
How breast-feeding might help suppress a relapse, despite a lack of medications, isn't clear. In people with MS, the body's immune system mistakenly attacks myelin, a substance that covers nerve fibers, according to the National Multiple Sclerosis Society.
Langer-Gould said that researchers have long known that women with MS often go into remission during pregnancy, which might indicate that hormones play some role in dampening the immune response that causes damage to the myelin. However, she said. the study's finding of continued MS remission during breast-feeding would suggest that pregnancy hormones, which decrease dramatically once the baby is delivered, cannot be the only reason for the suppression of MS.
"Previous research has ignored the postpartum factor, and what our study suggests -- if these findings can be repeated -- is that it's probably a factor that's common to pregnancy and lactation," Langer-Gould said.
Prolactin, a hormone that stimulates the production of breast milk and suppresses ovulation could be such a factor, suggested Patricia A. O'Looney, vice president of biomedical research at the National Multiple Sclerosis Society.
"There's been some interest in prolactin, which has been shown to stimulate repair and myelination, but we don't know the complete story yet," O'Looney said.
Whatever the reason behind it, Langer-Gould and her colleagues found that women who breast-fed exclusively for at least two months were five times less likely to have a relapse than those who didn't breast-feed at all.
The study included 32 pregnant women with MS and 29 age-matched women who were pregnant and healthy. Overall, women who chose to breast-feed exclusively began menstruating again at a later time than did women who did not breast-feed. In women with MS, the researchers found that a lack of menstruation due to breast-feeding was associated with a reduced risk of postpartum relapse.
Of the women with MS, 52 percent chose not to breast-feed, and 87 percent of them experienced a disease relapse within two months. Just 36 percent of women who were breast-feeding had an MS relapse within two months, the study found.
Langer-Gould said that even after adjusting the data to account for the possibility that women who were sicker before pregnancy would be less likely to breast-feed, the incidence of reduced relapse remained.
"The findings were still robust," she said.
O'Looney, who described the findings as "an interesting study that needs further confirmation," recommended that women with MS who are thinking about breast-feeding consult their doctors.
"Every case is different, and one should make the decision based on many things," she said. "Some women may have weakness in their arms and be physically unable to breast-feed. Women have to weigh all of their options, such as how active their disease was before pregnancy. And, even though this study was encouraging, the possibility of relapse wasn't eliminated. We never want to send the message that a woman who chooses not to or cannot breast-feed should feel guilty in any way."
More information
The National Multiple Sclerosis Society has more on pregnancy and MS.
