Breastfeeding Protects Against Postpartum Relapse in MS

Kristen M. Krysko, MD, MAS, clinical fellow of neurology, UCSF Weill Institute for Neurosciences

Kristen M. Krysko, MD, MAS

The results of a systematic review and meta-analysis suggest that women with multiple sclerosis (MS) can be protected from postpartum relapses by breastfeeding, although there remains a need for high-quality prospective studies as well as observational evaluations.

Conducted by Kristen M. Krysko, MD, MAS, clinical fellow of neurology, UCSF Weill Institute for Neurosciences, and colleagues, the study reported that those with MS who breastfed experienced 43% lower rates of postpartum relapse compared to those who did not. Notably, Krysko et al. wrote that “it is not possible to exclude residual confounding.”

“In this systematic review and meta-analysis of 24 studies that include 2974 women, there was a reduced rate of postpartum multiple sclerosis relapses in women who were breastfeeding compared with those who were not breastfeeding, with a stronger benefit of exclusive rather than nonexclusive breastfeeding,” the authors wrote.

Ultimately, 16 of the citations identified were included in the meta-analysis, and they suggested that the pooled odds ratio (OR) from 15 studies for the association of breastfeeding with postpartum relapse was 0.63 (95% CI, 0.45—0.88; P = .006) compared to non-breastfeeding. Additionally, the pooled hazard ratio (HR) across 4 studies in the analysis was 0.57 (95% CI, 0.38—0.85; P = .006).

Those who breastfed were 37% less likely to have postpartum relapse, with moderate heterogeneity (I² = 48.2%; P = .02). When the data was restricted to the 6 studies which had a moderate risk of bias, the findings were similar, with a summary OR of 0.50 (95% CI, 0.34—0.73; P <.0001). Krysko and colleagues wrote that heterogeneity stayed moderate, but every point estimate pointed toward the benefit of breastfeeding (I² = 46.1%; P = .10).

READ MORE: MS Relapse Rates Decrease During Pregnancy, Increase Postpartum

“There was moderate heterogeneity between studies regarding the association between breastfeeding and postpartum relapses, even when limiting to higher-quality studies,” Krysko and colleagues wrote. “This heterogeneity was mostly explained by the variable duration of follow-up postpartum, ranging from 3 to 12 months, as there was no relevant heterogeneity when restricting to studies evaluating 3- and 6-month postpartum relapses.”

They noted that the postpartum follow-up duration heterogeneity was anticipated due to the varying effect over the postpartum year. As well, there no relevant heterogeneity, when restricted to studies published after 2010, with the most consistent benefit of breastfeeding, demonstrated in recent studies.

The annualized relapse rate (ARR), only reported in 5 of the studies, was lower for those who breastfed, ranging from 0.49 to 1.2 (absolute difference range, 0.1 to 1.2). In total, 13 studies reported a summary risk ratio of 0.75 (95% CI, 0.60—0.94; P = .01), with 4 studies reporting an adjusted hazard ratio (HR) of 0.57 (95% CI, 0.38&shy;—0.85; P = .006), though with heterogeneity y (I² = 57.5%; P = .07).

When stratifying pre-pregnancy ARR below and above the median of 0.58 in preplanned subgroup analysis, there was less heterogeneity (I² = 27.2%; P = .23) and more benefit of breastfeeding in the studies with higher pre-pregnancy ARR (summary OR, 0.51; 95% CI, 0.34-0.78; P = .002) than those with lower pre-pregnancy ARR (I² = 52.2%; P = .05; summary OR, 0.72; 95% CI, 0.41—1.25; P = .24)

“However, meta-regression did not reveal a statistically significant association between pre-pregnancy ARR and ORs of the studies, although there was somewhat more suggested benefit of breastfeeding in studies with higher baseline ARR,” Krysko et al. wrote.

These findings echo those of a population-based study presented earlier this year by Annette Langer-Gould, MD, PhD, of Kaiser Permanente Southern California, which included 375 women with MS with 466 documented pregnancies from 2008 through 2016. Langer-Gould and co-investigators observed a decline in ARR from pre-pregnancy (0.39) to during pregnancy (0.14-0.07; P <.0001); however, they did not observe any rebound disease activity in the postpartum period. Overall, ARRs were down slightly in the first 3 months of the postpartum period (0.27, P =.02), and returned to pre-pregnancy rates at 4 to 6 months postpartum (0.37). As well, those who exclusively breastfed saw a reduced risk for postpartum relapse (adjusted hazard ratio 0.58; P =.01), yet those who resumed modestly effective DMTs saw no effect on relapse risk (P =86).²

“Despite the reduction in postpartum relapses with breastfeeding, ARRs remained fairly high postpartum, highlighting the need to identify additional strategies to prevent postpartum relapses,” Krysko and colleagues concluded. “We believe further study is required to evaluate the duration of benefit associated with breastfeeding and the safety of breastfeeding during treatment with disease-modifying therapies because treatment appears to be a key barrier to breastfeeding for women with MS.”

REFERENCES

1. Krysko KM, Rutatangwa A, Graves J, et al. Association Between Breastfeeding and Postpartum Multiple Sclerosis Relapses A Systematic Review and Meta-analysis. JAMA Neurol. Published online December 9, 2019. doi: 10.1001/jamaneurol.2019.4173.

2. Langer-Gould A, Smith J, Albers K, et al. Pregnancy-related relapses in a large, contemporary multiple sclerosis cohort: no increased risk in the postpartum period. Presented at: 2019 American Academy of Neurology Annual Meeting. May 4-10, 2019; Philadelphia, PA. Abstract S6.007.