Optimal seasonality of conception inferred from monthly marriage and birth time series in populations with no contraception

Abstract

The seasonality of conception for populations of the past using no contraception has remained a terra incognita. First, the influence of that of marriages on the seasonality of births is highlighted, taking into account the different stages in women's reproductive lives and the presence of successive cohorts of unequal size. Second, the age‐dependent and time‐dependent monthly distribution of conception is disentangled from monthly marriage and birth time series by means of stochastic optimization under a Leslie recursion with time‐varying and age‐varying probability of conception. The application to Armenian‐Gregorians in the Don Army Territory (South Russia) from 1889 to 1912 reveals strong consistency between reconstructed conception, mean age at marriage, and fertility time series. Copyright © 2017 John Wiley & Sons, Ltd.