A new study provides support for the notion that low maternal vitamin D levels during pregnancy could increase risk of MS in the offspring, Munger et al. identified 193 individuals with MS whose mothers had provided a serum sample from the pregnancy with the affected child; the serum vitamin D levels in these samples were compared with those from mothers of 331 controls. On average, samples from both groups were in the insufficient vitamin D range; however, mean vitamin D levels were lower in the case samples (13.86 ng/ml) than in the control samples (15.02 ng/ml), and vitamin D deficiency (defined as <12 ng/ml) was linked to a twofold increase in the risk of MS.