Never before have we seen so many children with allergies, eczema, and asthma. Our children’s immune systems are challenged like never before with an intense vaccine schedule This seems to have the effect of shifting the immune system from cell-mediated to allergic, as does the lack of exposures to allergens early in life as a result of the clean environment of the modern lifestyle. This has resulted in a relative preponderance of the TH2 arm of the immune response due to the lack of immunological shift of allergen-specific responses from the TH2 to the TH1 phenotype. This is the basis of the hygiene hypothesis, and combined with the increasing allergens that may be a result of global warming, we may be in for a huge rise in allergies in the years to come.
I recommend probiotics from birth (actually to be started in the third trimester) and earlier introduction of foods starting at 3-4 months age.
Read more about this here: http://www.cnn.com/2013/03/12/health/allergies-global-warming/index.html?hpt=hp_c3