An investigation of the timing pattern of childbearing

This paper reports an investigation of the relation between the number of live births during a woman's reproductive life-cycle and her ages at those births. Four samples of women from the United States and from the Philippines are used. The timing patterns of childbearing in these samples display several striking regularities. In all samples childbearing tends to occur in the centre of the fecund period irrespective of the number of children, so that the mean age at childbearing is essentially independent of final parity. In addition, the timing patterns are symmetric around the mean age at childbearing. Most important of all, the patterns are very alike in the different samples examined, despite large differences between average family size, methods used to regulate fertility, and economic, social, and cultural characteristics in the different populations.