However, it is also thought that contracting some childhood infections - which are often readily spread in environments such as playgroups where children are in close contact with each other - may prime the immune system against leukaemia.
Conversely, if the immune system is not challenged in early life, this is thought to raise the risk of an inappropriate response to subsequent infections, making the development of leukaemia more likely.
Wow, so those dreaded working moms, putting their kids in... gasp... daycare? Probably less likely to have kids who develop leukemia. Take that, Lurleneverse!