New mothers with MS are less likely to have a relapse within 6 months of delivery if they breastfeed their babies exclusively for at least 2 months, according to the findings of a prospective study of 201 women published online Aug. 31 in JAMA Neurology.
“Our findings indicate that women with MS should be supported if they choose to breastfeed exclusively since it clearly does not increase the risk of postpartum relapse. Relapse in the first 6 months post partum may be diminished by exclusive breastfeeding, but once regular feedings are introduced, disease activity is likely to return,” wrote Dr. Kerstin Hellwig of Ruhr-University Bochum (Germany) and her colleagues (JAMA Neurol. 2015 Aug 31. doi: 10.1001/jamaneurol.2015.1806).
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The effect of breastfeeding on postpartum MS relapse has been controversial. Some studies have found that exclusive breastfeeding for at least the first 2 months might be beneficial, while others – studies that “defined breastfeeding crudely and/or measured breastfeeding retrospectively,” the authors said – found no protective effect.
The 201 women in the study had relapsing-remitting MS for a median of about 4.5 years and had voluntarily enrolled while pregnant in the German MS and pregnancy registry. They completed a series of questionnaires during pregnancy and the first post partum year.
Overall, 120 women (59.7%) intended to breastfeed exclusively for at least 2 months; 42 (20.9%) combined breastfeeding with supplemental feedings within the first 2 months; and 39 (19.4%) did not breastfeed; 178 (88.6%) reported using disease-modifying therapies before pregnancy, most often glatiramer acetate or interferon beta.
Among the 81 women who did not breastfeed or who supplemented breastfeeding early on, 31 (38.3%) had an MS relapse within the first 6 post partum months, compared with 29 women (24.2%) among the 120 who breastfed their children exclusively (adjusted hazard ratio, 1.70; 95% confidence interval, 1.02-2.85; P = 0.04).
The researchers described exclusively breastfeeding as acting like a “modestly effective treatment with a natural end date.”
“During exclusive breastfeeding, the pulsatile release of gonadotropin-releasing hormone and luteinizing hormone is suppressed with a corresponding suppression of the growth of ovarian follicles resulting in lactational amenorrhea and anovulation. Shortly after the breastfeeding frequency is reduced (1 or 2 regularly replaced breastfeeding meals are sufficient to interrupt this cycle), the ovarian activity resumes with the return of menses,” Dr. Hellwig and her associates wrote.
They also speculated that the “hormonal changes leading to anovulation might play a key role since women with MS are less likely to receive the diagnosis during their anovulatory years (childhood or after menopause) and women with MS were found to be more likely to experience relapse shortly before menstruation.”
The mean age in the study was about 31 years, but women who breastfed exclusively tended to be older than their peers and less likely to have received disease-modifying therapies before or at the time of conception. The first postpartum menses among exclusive breastfeeders came at a median of 185 days vs. 64 days for other women.
“In the present study, we observed that an earlier return of menses was associated with a higher risk of relapse in the first 6 months post-partum,” the authors wrote.
The work was funded by the German Research Foundation. The German MS and pregnancy registry was partly supported by Bayer Healthcare, Biogen Idec, Merck Serono, Novartis Pharma, and Genzyme Pharmaceuticals. Five of the researchers reported receiving speaker honoraria or other financial support from pharmaceutical companies.