Although I am not a follower of astrology in any way, I do believe that the time of the year when a person is born has influence on some aspects of who he is. It is a secret hobby of mine to guess a person’s approximate birthday based on my personal impression. While playing this game I noticed that most people I know who severely suffer from eczema, asthma, psoriasis, food allergies and/or auto immune disease (e.g. vtitiligo) are born in late summer/early fall (end of August / beginning of October).
Unexpected support for this observation came yesterday when I read again passages in David Atherton’s book  (thank you Cindy for recommending this book!). Atherton states in the beginning of chapter 14 that “[…] risk of eczema differs with month of birth, those children born during the autumn months being at the greatest risk”. He further suggests that this “reflects heavier exposure to house dust mite droppings at this time of the year”.
I wonder if the dust mite droppings are enough of an explanation. Especially because in late summer/early fall it is often still very warm. Our son J. had first signs of dry skin and cradle cap long before the cold weather forced us inside. I rather want to put forward an alternative hypothesis, that the increased risk of atopy or immune impairment is associated with some deficiency in the mother during the first three months of pregnancy, possibly a vitamin D deficiency. Some support for this hypothesis might come from a recent study [2,3] that shows that in the US the risk for eczema is highest in people who are “living in metropolitan areas, those with a higher household-education level, and those belonging to black ethnic groups”. Aren’t those the same groups that are generally associated with vitamin D deficient?
A quick search on PubMed for “eczema vitamin d” didn’t find much, but in one Japanese study  children of mothers who took a higher dose of vitamin D “had a significantly reduced risk of wheeze and eczema” (according to the abstract; I don’t have access to the full text version). Wouldn’t that be great if one could lower the risk of eczema in children simply by supplying the mother with enough vitamin D? I still have to read more on that, but it seems to me that there has not been much research done in this direction. Please let me know if you came across a study that is more conclusive.
 David J. Atherton (1994) Eczema in childhood. The facts. Oxford Medical Publications, Oxford University Press.
 Shaw, TE, Currie, GP, Koudelka, CW, Simpson, EL (2011). Eczema prevalence in the United States: data from the 2003 National Survey of Children’s Health. J. Invest. Dermatol., 131, 1:67-73.
 Williams, HC (2011). Eczema across the World: The Missing Piece of the Jigsaw Revealed. Journal of Investigative Dermatology 131, 12–14. Free Access
 Miyake, Y, Sasaki, S, Tanaka, K, Hirota, Y (2010). Dairy food, calcium and vitamin D intake in pregnancy, and wheeze and eczema in infants. Eur. Respir. J., 35, 6:1228-34.