Randall W
Department of Psychology, University of Iowa, Iowa City 52242.
Int J Biometeorol. 1993 Feb;37(1):52-60. doi: 10.1007/BF01212768.
Twenty-two years of monthly values of birth data for the USA, 1967 through 1988, were analyzed by visual inspection. The data were transformed to remove the influence of length of month and of linear trend, and the values were lagged 9 months to approximate the time of conception. Then, 11-year monthly averages were obtained and plotted as standard scores. Thus two 11-year sets of data were independently analyzed, providing the opportunity of replication. Four distinct temporal patterns were found, differing in month of occurrence of the initial trough and peak and the relative sizes of the two troughs; these characteristics of the temporal pattern change systematically with latitude in the eastern and midwestern states. Data from two other continents, the United Kingdom and Australia, also were analyzed using the same method and found to exhibit a temporal pattern during the year similar to the northern states of the USA. Two biologically relevant variables, temperature and photoperiod, were considered as possible controllers and regulators of the annual rhythmicity. Comparisons of the trends in conceptions with these environmental variables, and inspections of the temperatures and photoperiods at which peaks and troughs in conceptions were found, indicated that these environmental variables could not account for the annual rhythmicity in conceptions.
对1967年至1988年美国22年的月度出生数据进行了目视检查分析。对数据进行了转换，以消除月份长度和线性趋势的影响，并将数据滞后9个月以近似受孕时间。然后，获得11年的月度平均值并绘制为标准分数。因此，对两组11年的数据进行了独立分析，提供了重复验证的机会。发现了四种不同的时间模式，它们在初始低谷和高峰出现的月份以及两个低谷的相对大小方面存在差异；这些时间模式的特征在东部和中西部各州随纬度有系统地变化。还使用相同的方法分析了来自其他两个大陆，即英国和澳大利亚的数据，发现它们在一年中的时间模式与美国北部各州相似。考虑了两个与生物学相关的变量，即温度和光周期，作为年度节律可能的控制和调节因素。将受孕趋势与这些环境变量进行比较，并检查发现受孕高峰和低谷时的温度和光周期，结果表明这些环境变量无法解释受孕的年度节律。
