Economic analyses of the spacing of births.
分析了生育间隔的经济学意义，指出研究年轻女性生育间隔对理解整体生育率下降、人口增长及儿童健康至关重要，并探讨了动态模型在解释生育行为与劳动力参与互动中的必要性。
In the last several years, economists and demographers have been increasingly interested in the spacing of births. This interest has arisen partly because younger women are often observed to play an important role in the decline of fertility in a population. Their behavior cannot be analyzed adequately within a static model of completed family size, because they cannot be assumed to have completed their fertility. The observations on these young women are censored by the survey date and reflect decisions on the spacing of births as well as the desired number of births. Thus, even if one had no interest in the spacing of births, per se, an analysis of spacing is necessary to detect whether or not changes in fertility behavior at younger ages will be reflected some years later in completed family size. The spacing of births can be interesting for its own sake. From an empirical standpoint, spacing can affect the rate of growth of a population through its effect on the average time between generations. There is also some evidence that the spacing affects the health of the child in its early years. Moreover, one might expect that as the variance of completed family size decreases in developed countries, many of the behavioral responses to socioeconomic conditions may come in the timing of births. The effort spent on developing dynamic models of fertility can also be justified on theoretical grounds because some questions cannot be handled within a static framework. How the effect of explanatory variables on fertility changes at different ages and how the spacing decision interacts with female labor force participation are two important questions which come readily to mind.