Abstract
Between October 6, 1997 and April 30, 1999, 5011 births (mean: 8.76 per day) were registered in the city of Passo Fundo, South Brazil. The sequence of 572 daily birth numbers was not random (iteration test). Neyman distribution (m = yen ) showed the best fit. Clusters of days with higher birth numbers alternated with days with low numbers of births. Periodogram analysis revealed a significant periodicity of 6.98 days. The cosinor regression, testing 10 a priori supposed period lengths, found significant seasonality peaking in August-September and significantly highest birth numbers on Thursdays. Among the lunar and solar rotation cycles, the tropic lunar cycle and its 4th harmonic were most pronounced, in agreement with results concerning natality in Germany obtained by Svante Arrhenius in the 19th century. These findings confirm Derer-Halberg's concept of multiseptans. In addition to cycling, a significantly increasing linear trend with a daily increase of 0.0045 births was encountered. This documents a growth of the population in agreement with national statistical data.
Highlights
Cosmogeophysical changes undoubtedly influence many events occurring on earth
Clusters of days with higher birth numbers alternated with days with low numbers of births
Periodogram analysis revealed a significant periodicity of 6.98 days
Summary
Cosmogeophysical changes undoubtedly influence many events occurring on earth. The seasons are the most straightforward example that the position of earth in relation to the sun induces changes in temperature and other parameters on our planet. The influence of cosmogeophysical factors on living organisms has long been studied, sometimes with contradicting results. Pronounced and persistent seasonal patterns in fertility have been observed in virtually all human populations. This seasonality increased in the 20th century in some high income, low fertility populations such as that of Sweden [2]. Temperature did not play any role in explaining the pronounced June-July peak in conceptions in this country.
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