WEDNESDAY, July 6 (HealthDay News) -- Hopes that breast-feeding can reduce flare-ups of multiple sclerosis have been dimmed by recent research in Italy.
Researchers at the University of Florence found no support for prior studies connecting breast-feeding with lower disease activity for women with the degenerative nerve disorder commonly known as MS.
Instead, they determined that women who were sicker tended not to breast-feed, leading to the conclusion that some breast-feeding mothers had fewer relapses simply because they were healthier.
"Breast-feeding should not be encouraged as a protective factor without an accurate evaluation of the specific patient characteristics," said Dr. Emilio Portaccio, lead author and neurologist in the university's department of neurology. "Our study is important due to a lack of a consensus on whether breast-feeding should be advised against in order to resume therapy soon after delivery."
Women with MS are cautioned not to take medications while breast-feeding. The findings suggest that nursing may not be possible for women "with high disease activity," said Portaccio. Those women should be counseled that MS drug treatment soon after delivery should be an option, the authors said.
Multiple sclerosis, a progressive autoimmune disorder characterized by deterioration in physical coordination, affects about 400,000 people in the United States. It strikes women twice as often as men, with symptoms varying greatly from one person to another, according to the National Multiple Sclerosis Society.
Typically, the disease goes into remission, sometimes for long periods of time, and flare-ups during pregnancy are rare, according to the society.
"The reason is not yet fully understood," said Portaccio.
But the effect of pregnancy on the course of the disease is "at best neutral," Portaccio said, noting that other autoimmune disease activity also declines while women are carrying children. During that time, an immune system "switch" changes from a "pro-inflammatory status to an anti-inflammatory status that promptly reverts after delivery." Symptoms then increase to an "even higher" level for a few months. Pregnancy is not believed to cause any long-term worsening of the disorder, however.
Several drugs are used to fight MS, which attacks myelin, the protective covering of nerve cells, causing inflammation. They are not considered safe for use during pregnancy, however.
For their study, the researchers looked at 298 women with full-term pregnancies from 2002 to 2008 at 21 MS treatment centers throughout Italy. Of those, about 34 percent breast-fed their babies for at least two months. The remaining mothers, who breast-fed for zero to two months, were labeled the non-breast-feeding group.
Follow-up lasted for a year. After adjusting for factors such as age and level of disability, the researchers found no significant difference in relapse rates between the breast-feeding and non-breast-feeding groups.
The only predictor of postpartum disease activity was the number of relapses before and during pregnancy, the researchers found.
The study, published online July 6 in Neurology, was conducted on behalf of the MS Study Group of the Italian Neurological Society.
The findings are "in line with what one might expect," said Dr. Fred Lublin, a neurologist at Mount Sinai Medical Center in New York City. "Healthier women tended to breast-feed."
The study "did not resolve the issue of breast-feeding," added Lublin, who is also director of the Corinne Goldsmith Dickinson Center for Multiple Sclerosis at Mount Sinai. "These studies are all observational and it's hard to draw a conclusion of cause and effect from an observational study." A controlled study is needed, he said.
One expert expressed concern about the study's methodology. Dr. Emmanuelle Waubant, a neurologist at the University of California San Francisco Multiple Sclerosis Center, said that grouping women who had breast-fed for less than two months with those who did not breast-feed at all could have affected the findings.
"Breast-feeding affects hormone production," which could affect disease activity, said Waubant, who is also an associate professor of neurology at the university.
But Lublin, who did not share that concern, said the researchers had used established criteria for group selection set by the World Health Organization.
To learn more about pregnancy and multiple sclerosis, visit the National Multiple Sclerosis Society.