The stable births resulting from a time dependent change between two net maternity functions.
The asymptotic birth rate for a one-sex population in which the net maternity function changes to one of bare replacement was first discussed by Keyfitz and has since been studied by several authors. The present generalization allows for a time dependent transition from any net maternity function to another and, thus, includes all previous models.
D001723:Birth Rate; D005260:Female; D006801:Humans; D008433:Mathematics; D011247:Pregnancy; D013997:Time Factors