SEATTLE—Women with multiple sclerosis (MS) may be able to reduce their risk for postpartum relapses by breastfeeding, according to findings that were presented at the 61st Annual Meeting of the American Academy of Neurology.
Previous studies have shown that breastfeeding may offer only limited protection against postpartum relapses in women with MS; however, these studies did not account for early supplemental infant formula feedings. Therefore, researchers from Stanford University and Northern California Kaiser Permanente Health Care System were interested in determining the effect of exclusive breastfeeding on risk of postpartum MS relapses, compared with not breastfeeding or breastfeeding combined with supplemental infant formula feedings.
“We prospectively followed 32 pregnant women with MS and 29 age-matched, pregnant controls and conducted structured interviews to assess clinical, menstrual, and breastfeeding history during each trimester and two, four, six, nine, and 12 months postpartum,” said Annette Langer-Gould, MD, a research scientist and neurologist at Kaiser Permanente Southern California. Patients were enrolled between 2002 and 2005.
Exclusive breastfeeding was defined as at least one bottle of breast milk per day, without regular supplemental infant formula feedings, for at least two months postpartum. “We chose the two-month cutoff, because we wanted it to be something that women could realistically achieve,” said Dr. Langer-Gould.
Exclusive Breastfeeding Appears to Be Protective
The researchers found that “fewer women with MS breastfed at all, compared to their healthy matched controls.” Fifty-two percent of women with MS did not breastfeed exclusively or began regular supplemental infant formula feedings within two months postpartum; of these, 87% had a postpartum relapse. In comparison, 36% of women who breastfed exclusively for at least two months postpartum had a relapse—in most cases, much later than women who did not breastfeed exclusively.
Seventy-three percent of women who decided to forego breastfeeding stated that they did so to resume MS therapies. Dr. Langer-Gould noted that more women who did not exclusively breastfeed had used immunomodulatory therapies in the year prior to becoming pregnant and might have had more frequent relapses prior to becoming pregnant as well, compared with women who breastfed exclusively. However, the effect of exclusive breastfeeding was still highly protective even after taking these factors into account.
Women who resumed MS therapies and did not breastfeed exclusively within the first two months postpartum had a significantly higher risk of postpartum relapses than women with MS who did not restart medications, regardless of breastfeeding status, noted Dr. Langer-Gould. These findings are interesting, she said, particularly because “our data certainly show that there is a belief that pregnant women with more severe disease should resume medications instead of breastfeeding after giving birth.”
Dr. Langer-Gould hypothesized that anovulation may play a role in protecting against postpartum relapse. Experimental autoimmune encephalitis models have shown that all states of anovulation appear to be protective against relapse, potentially explaining why pregnant women and women who exclusively breastfeed might show protection against relapse, she said. She noted that women who breastfed exclusively in the current study had a later return of menses.
Weighing the Risks and Benefits of Resuming Medications
“Our findings call into question the benefit of choosing not to breastfeed or stopping breastfeeding early to start taking MS therapies,” stated Dr. Langer-Gould. “Our study found no evidence that breastfeeding is harmful or that resuming MS medications is helpful in preventing postpartum relapses. Larger studies need to be done to establish whether breastfeeding exclusively is actually better than resuming medications.
“Future studies should also establish the safety of these medications during lactation, as has been done for antidepressants, which is a different concern than safety during pregnancy. That way, women with MS wouldn’t have to choose between what might be best for them and what is best for their baby,” she concluded.
—Karen L. Spittler