A brief study of age specific birth proportions,Japan and Singapore

The suitability of age-specific birth proportions (ASBP), or percentage distribution of births, as a rough and ready index of fertility change was analyzed by establishing a theoretical framework for its limitations and uses. The discussion suggested that the utility of ASBP as an indicator of fertility change depends on the characteristics and behavior of the population being considered. The concept was then empirically applied to birth trends in Japan and Singapore for 2 different time periods. Analysis suggested that ASBP trends in Japan reflected changes in age-specific fertility rates relative to general fertility rate as well as trends in parity distribution. The Singapore analysis was more complicated, raising different issues. As very limited empirical work has been done on ASBPs, the utility of ASBPs as an indicator of fertility change cannot be definitely ascertained. It was suggested however that ASBP trends may be applicable in countries where the age distribution of fertile-aged women is fairly stable. More empirical research should be done on ASBP trends in other countries, the behavior of A matrix as discussed in this paper, and useful empirical relationship of ASBP with other fertility measures.