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Month of birth linked to immune health and multiple sclerosis

Posted on: April 9, 2013   by  Vitamin D Council


A newborn’s immune system development and risk of multiple sclerosis may be influenced by their month of birth, according to new research published in JAMA Neurology.

A number of studies have shown that the month you are born may influence your risk of developing multiple sclerosis (MS), the development of which is thought to be a result of an interaction between genetic predisposition and environmental factors. MS is a neurological condition in which the body’s immune system attacks the central nervous system causing problems with muscle control, vision, and memory. We have reported on similar studies in the past that support this research.

The “month of birth” effect is especially evident in England, where the risk of developing MS peaks in people born during the month of May, and decreases in those born in November.

Researchers collected cord blood samples from 50 babies born in November and 50 born in May between 2009 and 2010 in London. The researchers measured levels of vitamin D and autoreactive T-cells. T-cells are white blood cells which are involved in the body’s immune response. However, some T-cells are autoreactive and capable of attacking the body’s healthy cells; contributing to the risk of autoimmune diseases like MS.

The authors report that the May newborns had significantly lower vitamin D levels and significantly higher autoreactive T-cell levels, compared to the November babies.

“By showing that month of birth has a measurable impact on in utero immune system development, this study provides a potential biological explanation for the widely observed ‘month of birth’ effect in MS. Higher levels of autoreactive T-cells, which have the ability to turn on the body, could explain why babies born in May are at a higher risk of developing MS. The correlation with vitamin D suggests this could be the driver of this effect.”

The authors remind us that association does not mean causation, and that long-term trials are needed to assess the effect of vitamin D supplementation in pregnant women and its impact on immune function.


Disanta G, Watson CT, Meier UC, Ebers GC, Giovannoni G, Ramagopalan SV. Month of birth and thymic output. JAMA Neurology. April 2013.

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