James W H
MRC Mammalian Development Unit, University College London.
J Biosoc Sci. 1990 Jan;22(1):113-9. doi: 10.1017/s0021932000018423.
During the first half of this century, the seasonal pattern of births in European countries showed a major peak in the spring and a minor peak in the autumn. In contrast, the pattern in the US was of a minor peak in spring and a major peak in autumn. Over the last 20 years, the pattern in England and Wales has changed to resemble the US pattern, and the same seems to be true of several other European countries. A hypothesis is offered to account for the difference between the European and the US patterns and for the change from one to the other in some countries. The magnitude of seasonality correlates positively with latitude: it is suggested that this is partially consequent on variation in luminosity.
在本世纪上半叶，欧洲国家的出生季节模式呈现出春季的一个主要高峰和秋季的一个次要高峰。相比之下，美国的模式是春季有一个次要高峰，秋季有一个主要高峰。在过去20年里，英格兰和威尔士的模式已转变为类似于美国的模式，其他几个欧洲国家似乎也是如此。本文提出了一个假说，用以解释欧洲和美国模式之间的差异以及一些国家从一种模式向另一种模式的转变。季节性的程度与纬度呈正相关：有人认为，这部分是由于光照度的变化所致。
