Contraception and Fertility: Household Production Under Uncertainty
Robert T. Michael, Robert J. Willis
NBER Working Paper No. 21
Over the past century fertility behavior in the United Stated has undergone profound changes Measured by cohort fertility the average number of children per married woman had declined from about 5.5 children at the time of the Civil War to 2.4 children at the time of the Great Depression. It is seldom emphasized however that an even greater relative change took place in the dispersion of fertility among these women: the percentage of women with, say, seven or more children declined from 36% to under 6%. While students of population have offered reasonably convincing explanations for the decline in fertility over time, they have not succeeded in explaining the fluctuations in the trend and have made surprisingly little effort to explain the large and systematic decline in the dispersion of fertility over time. In this paper we attempt to study contraception behavior and its effects on fertility. One of the effects on which we focus considerable attention is the dispersion or variance in fertility. Our analysis is applied to cross-sectional data but it also provides an explanation for the decline in the variance in fertility over time.