Fertility effect of seasonal migration and seasonal variation in fecundability: Test of a useful approximation under more general conditions

A demographer J. Menken recently demonstrated that the asymptotic birth rate calculated by a family-building model for a population with seasonal variation in fecundability due to such causes as seasonal separation of spouses is close to the birth rate of a population in which fecundability is kept constant at the mean of the seasonally varying values. This theory was tested and proven with a set of complex fertility simulations. Results hold up well for various combinations of numbers of months of annual separation. These findings are important for demographers because it seems that seasonally varying fecundability can be allowed for without simulating this variation directly in family-building models.