Birth month and risk of glioma in adults: a registry-based study in Bavaria.

The aim of the present study was to evaluate the possible seasonality of birth in adult patients suffering from glioma. For this purpose, data from the database of the population-based cancer registry of Bavaria (Germany) were retrieved. For the period 2002-2005, we identified a total of 2174 patients born between 1931 and 1986 diagnosed with malignant glioma. Statistical analyses failed to document a significant annual periodicity of glioma risk in either men or women with respect to birth month in the observed cohort. Thus, we found no association between month of birth and the risk of glioma. In contrast, an analysis of the official birth rate data of Bavaria revealed marked annual variation in birth rates up until 1965, which decreased markedly in prominence in the years thereafter. Our findings confirm the results of a recent similar study conducted in The Netherlands. Therefore, we support the hypothesis of possible etiological factors of glioma acting in adulthood rather than in the perinatal period.