A general model for analyzing the effect of nuptiality on fertility

Abstract

The influence of nuptiality on marital fertility in situations where birth control is and is not practiced is examined in this paper. Where no deliberate control of marital fertility is practiced changes in nuptiality effect change in age specific fertility only by affecting the proportions married at each age. The comparative statics (comparison of initial and final equilibrium states) and the dynamic path from initial to final states were analyzed for such populations; a reduction in total fertility of about 5% for each year of increase in the mean age of marriage was found. To examine the case of deliberate control of marital fertility a model in which the degree of control at each age is a function of the duration of marriage was used. Since different marriage patterns imply different duration distributions of the married population for a given current age marital fertility itself is affected by changing nuptiality patterns. The principal finding of an analysis of the comparative statics and dynamic aspects of changing nuptiality was that the greater the degree of duration-dependent fertility control the less the permanent change in total fertility produced by nuptiality change and the more pronounced the transient change. The article also assesses the substitution of recorded age distributions of 1st births for data on age of entry into unions; a model distribution of 1st birth identical with the model distribution of 1st marriages is found to be useful. An appendix examines the representation of the fertility of marital status categories by aggregate measures or indices using the European Fertility Study as an illustrative case.