By Karla Gale

NEW YORK (Reuters Health) - After pregnancy, women with multiple sclerosis may substantially reduce their risk of relapses if they breast-feed their infants, without adding supplemental formula feedings, for at least 2 months.

That's the conclusion of researchers in California, who also found that women who restarted multiple sclerosis medications within 2 months after birth actually had a higher rate of relapse than other women, regardless of whether they breast-fed or not.

The research team at Stanford University in Palo Alto and at Northern California Kaiser Permanente Division of Research, Oakland, will report their findings on April 28 at the American Academy of Neurology's 61st annual meeting in Seattle.

"Women with multiple sclerosis have fewer relapses during pregnancy and an unusually high risk of relapse in the first 3 to 4 months postpartum," Dr. Annette Langer-Gould, who will be presenting the research, told Reuters Health.

"Whether breast-feeding is beneficial or harmful in multiple sclerosis is not certain," she continued. "The few previous studies in women with multiple sclerosis have suggested that breast-feeding has no effect, but they did not distinguish between exclusive and non-exclusive (with formula) breast-feeding. Current treatments used to reduce the risk of relapses in multiple sclerosis are not recommended for use during pregnancy or lactation and their effect on postpartum relapses have never been studied."

"Thus, patients have to choose whether to forego nursing (and the health benefits to the infant) and resume treatment, or nurse and remain untreated, without clear evidence to support either practice."

To shed light on these issues, Langer-Gould's team followed 32 pregnant women with multiple sclerosis throughout their pregnancies and for the first postpartum year.

Forty-eight percent of the women breast fed exclusively for at least 2 months, while the remaining 52 percent did not breast-feed or else began regular supplemental feedings within 2 months.

The rate of relapse was 87 percent among those who did not breast-feed exclusively versus 36 percent of those who did. After accounting for disease severity and age, women who did not exclusively breast-feed were seven-times more likely to suffer a relapse than those who did.

Exclusive breast-feeding causes body changes, such as a loss of menstrual periods, that may reduce inflammation, Langer-Gould explained. After supplemental infant feedings are introduced, these changes disappear.

Langer-Gould said she was "definitely surprised" by the finding that women who resumed multiple sclerosis therapies within 2 months postpartum had a higher risk of relapses. "Our data suggest that it is most likely because they are not breast-feeding."

If findings from this small study are confirmed in larger trials, she suggests that "physicians may want to consider extending maternity leave for at least 2 months for women with multiple sclerosis so they can breast-feed exclusively."

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