How birth control affects births

Abstract

Advances have been made in the technique of contraception, and these are being adopted in various parts of the world. The effect that the adoption of the loop or the pill has in averting births that would occur without protection, or with older forms of contraception, is a main interest of contemporary demography. To estimate this effect one must regard conception and birth as a renewal process for the individual woman. Though the models of the succeeding pages are very simple, they show the lines along which correct calculations can be made. Further advances in theory are producing more realistic models, and large amounts of data collection now going forward provide better estimates of such parameters of the process as probability of conceiving in a given month without protection and with various types of contraceptives.