A mathematical model of human population reproduction through marriage

We develop a linear one-sex dynamical model of human population reproduction through marriage. In our model, we assume that a woman can repeatedly marry and divorce but only married women produce children. The iterative marriage process is formulated by a three-state compartmental model, which is described by the system of McKendrick equations with the duration-specific birth rate by age at marriage. In order to see the effect of changes in nuptiality on fertility, new formulae for the reproduction indices are given. In particular, the total fertility rate (TFR) is considered as the product of the indices of marriage and marital fertility. Using the vital statistics of Japan, we can show that our model can provide a reasonable estimate of the Japanese TFR, and its possible future scenario.