Medications used to treat MS are not recommended for use during pregnancy or breastfeeding. Therefore, women with MS who give birth must choose between nursing and resuming MS treatment.
For the study, Annette Langer-Gould, M.D., Ph.D., then of Stanford University School of Medicine, Stanford, Calif., and now of Kaiser Permanente Southern California, Pasadena, and colleagues examined 32 pregnant women with MS and 29 pregnant women without MS who were the same age.
The participants were interviewed about clinical, menstrual and breastfeeding history during each trimester and again two, four, six, nine and 12 months after they gave birth.
Also, neurological examination findings were collected from the physicians of women with MS.
More healthy women than women with MS breastfed (96 percent vs. 69 percent), and among those who did breastfeed, women with MS were more likely to begin daily formula feedings within two months after birth (30 percent compared with 18 percent).
"Of the 52 percent of women with MS who did not breastfeed or began regular supplemental feedings within two months postpartum [15 women], 87 percent [13 women] had a postpartum relapse, compared with 36 percent [five women] of the women with MS who breastfed exclusively for at least two months postpartum [14 women]," the authors said.
"Women with MS and healthy women who breastfed exclusively had significantly prolonged lactational amenorrhea [absence of menstruation], which was associated with a decreased risk of relapse in women with MS," they added.
The results suggest that women with MS should be encouraged to breastfeed exclusively for at least the first two months after birth instead of resuming medications, the authors note.
The study will appear in the August print issue of Archives of Neurology, one of the JAMA/Archives journals.