( TIME.com ) -- The month in which babies are born can affect how their immune systems develop , and even how vulnerable they are to autoimmune diseases . Scientists studying the neurological disorder multiple sclerosis , in which the body 's own immune cells destroy the protective coating around nerves and can lead to paralysis and loss of other functions , have long been puzzled by the `` birth month effect . '' Many patients with MS are born in the spring , and rates of the disease are lowest for those born in November . Some have speculated that insufficient levels of vitamin D , which the skin produces when exposed to sunlight , on the mom 's part could play a role , since babies born in May are gestated during the colder , darker months , while winter babies are in utero during the spring and summer . Now a study published in JAMA Neurology shows that this hunch may be correct , and suggests a mechanism for how the vitamin might be driving immune system development . TIME.com : Vitamin D not recommended post-menopause . Researchers in the UK studied 50 babies born in London in May and 50 babies born in November between 2009 and 2010 . They sampled blood from the newborns ' umbilical chords and recorded levels of vitamin D and a specific type of immune cell known as autoreactive T-cells . T-cells are the white blood cells that battle pathogens like bacteria and viruses , but autoreactive T-cells are aberrant versions that mistake the body 's own cells as foreign and attack them as they would an unwanted infection . TIME.com : Multiple Sclerosis drug may not slow disease . The researchers found that babies born in May had vitamin D levels that were 20 % lower than those in babies born in November , and almost double the amount of autoreactive T-cells . They speculate that vitamin D may be important in some way in educating T cells about how to recognize self cells ; this occurs in the thymus , and errors in the training could lead to higher levels of the destructive T cells . The connection between vitamin D and immune disorders first emerged from population studies that showed people who lived further away from the equator , in places with less sunlight , were at higher risk of developing MS . But the researchers caution that their results still do n't suggest that lower levels of the vitamin cause autoimmune disorders like MS . So it 's not clear yet whether supplements of vitamin D could help to lower rates of the disease â€ ” especially for those conceived in July and born in May . In fact , experts continue to debate how much vitamin D is appropriate for otherwise healthy people when it comes to preventing disease , since studies on the subject are conflicting . The Institute of Medicine currently recommends that adults get about 600 IU daily . TIME.com : After Jack Osbourne 's MS diagnosis . More research is needed to figure out whether pregnant women might need to take more vitamin D in order to strengthen their babies ' immune systems , but doctors now have a better understanding of what birth months have to do with how the immune system develops . This article was originally published on TIME.com . & copy 2012 TIME , Inc. TIME is a registered trademark of Time Inc. Used with permission .
Many patients with multiple sclerosis are born in the spring , not fall . Comment: New study shows the vitamin might be driving immune system development .