[Seasonal variations in the birth rate and conception rate within the last 200 years (author's transl)].
The monthly variations and the mean daily conception rates of 136,828 deliveries from 1803 to 1970 within the same population area are reviewed. It was found that the conception rate during the first half of the 19th century showed a rapid increase from its low during the winter to its maximum in May and that this pattern became much less pronounced in the 20th century. During the second half of the 20th century, the highest conception rate shifted for the first time to the summer and the third quarter of the year. In contradistinction to this development, the low of the conception rate during the winter from January to March is much less pronounced during the first half of the 20th Century and remains constant with the lowest conception rate in February into the second half of the 20th century. The importance of the influence of nature during the spring and winter and of the working and living patterns as well as the influence of family planning and recreational activities on the intensity of procreation in the human within the last 200 years is discussed.