Prolonged Breastfeeding Linked to Reduced Risk of Multiple Sclerosis

Baby being breastfed
Baby being breastfed
Previous research has shown a reduced risk for multiple sclerosis and relapse during pregnancy.

Prolonged breastfeeding is associated with a lower risk for mothers developing multiple sclerosis (MS), according to results from a case-control study published in Neurology.

There is conflicting research involving the impact of reproductive factors on MS risk. Breastfeeding duration along with total ovulatory years is a potentially modifiable factor that had not been assessed in previous MS studies. Further, there is evidence that the risk for MS relapse is lower during pregnancy and exclusive breastfeeding, possibly related to sex hormones or anovulation.       

In the current study, Annette Langer-Gould, MD, PhD, of the department of research and evaluation at Kaiser Permanente Southern California, and colleagues sought to investigate the association between breastfeeding duration or lower ovulatory years and risk for developing MS. The MS Sunshine study included patients with newly diagnosed MS or clinically isolated syndrome (CIS) (n=397) and matched controls (n=433). Participants were assessed for pregnancy, breastfeeding, hormone contraceptive use, age at menarche, age at menopause, and history of amenorrhea by in-person questionnaire.

Overall, women with live births who breastfed for 15 months or longer had a lower risk for MS/CIS compared with women who breastfed for 4 months or less (adjusted odds ratio [aOR] 0.47; 95% CI, 0.28-0.77; P =.003).

Likewise, menarche at 15 or older was associated with a lower risk for MS/CIS in this cohort (aOR 0.56; 95% CI, 0.33-0.96; P =.035). However, there were no significant associations between MS/CIS and total ovulatory years, gravidity, parity, amenorrhea, hormonal contraceptive use, and age at first birth.

The mechanism underlying the association between breastfeeding duration and MS risk is unclear. The investigators initially proposed that the relationship was tied to anovulation; however, this study did not find a reduced risk during other anovulatory states such as pregnancy and hormonal contraceptive use.

The investigators noted several limitations, including the possibility of recall bias and recall error with the case-control design of the study.

“Taken together with the existing literature, this study provides more evidence that women who are able to breastfeed their infants should be supported to do so. Among other maternal and infant health benefits, breastfeeding may reduce the mother’s future risk of developing MS and may even reduce the risk of MS in child,” the investigators wrote.

Disclosures: Drs Langer-Gould and Hellwig report multiple disclosures. See the study for a full list of disclosures.

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Langer-Gould A,  Smith JB, Hellwig K. Breastfeeding, ovulatory years, and risk of multiple sclerosis [published online July 12, 2017]. Neurology. doi:10.1212/WNL.0000000000004207