Pregnancy and breastfeeding are strongly associated with low vitamin D levels in women with MS, but these low vitamin D levels are not associated with an increased risk of postpartum MS relapses.
Women with multiple sclerosis (MS) have lower vitamin D levels during pregnancy and while breastfeeding; however, according to a November 8 online report released by the Archives of Neurology, these low vitamin D levels were not associated with a greater risk of MS relapse postpartum.
“During the last decade, low level of vitamin D, a potent immunomodulator, has emerged as an important risk factor for MS as well as other autoimmune diseases and certain cancers,” said Annette Langer-Gould, MD, PhD, and colleagues. “The observation that healthy pregnant and lactating women are at particularly high risk of vitamin D insufficiency, regardless of race, suggests that pregnant and nursing mothers with MS may have a higher risk of relapses.” However, they pointed out, it has already been well established that the risk of MS relapse decreases during pregnancy and increases during the postpartum period and that breastfeeding does not increase the risk of relapses.
Dr. Langer-Gould, at the time of the study at Stanford University School of Medicine and now at Kaiser Permanente Southern California’s Department of Research and Evaluation in Pasadena, and colleagues studied 28 pregnant women with MS identified through membership records of Kaiser Permanente Northern California or Stanford University outpatient neurology clinics. Participants donated blood and completed questionnaires at the beginning of the study, during their remaining trimesters of pregnancy, and regularly through the first year after birth.
Fluctuating Vitamin D Levels
Of the 28 women, 14 (50%) breastfed exclusively and 12 (43%) relapsed within six months after giving birth. During pregnancy, average blood levels of 25-hydroxyvitamin D (25[OH]D) were 25.4 ng/mL and were associated with season. After birth, levels remained low among women who were exclusively breastfeeding but rose significantly in the nonexclusive breastfeeding group regardless of season. By four and six months after childbirth, 25(OH)D levels were an average of 5 ng/mL lower among women who breastfed exclusively than among those who did not. However, these low postpartum vitamin D levels were not associated with risk of MS relapse. “If anything, by three to six months after childbirth, 25(OH)D levels were marginally higher among the women who relapsed within the first six months after childbirth compared with women who were relapse-free during the same period,” the researchers said. “We do not believe that higher vitamin D levels increase the risk of postpartum relapses, as the rise we observed did not appear to occur prior to the onset of symptoms and the findings were of marginal statistical significance after accounting for season. Instead, we think this apparent inverse association is a reflection of the fact that most of the women who relapsed in the study also did not breastfeed or did so only briefly.”
The Bottom Line for Women With MS
“Our finding that low vitamin D is not a risk factor for MS relapse in pregnant and lactating women suggests that increasing vitamin D levels during pregnancy and the postpartum period in women with MS is unlikely to affect the risk of postpartum relapse,” the researchers concluded. “Therefore, our findings imply that the recommended dose of vitamin D supplementation for women with MS during pregnancy and lactation should be the same as for women who are not.”