Bongaarts J
Stud Fam Plann. 1986 Sep-Oct;17(5):209-16.
Major fertility declines in developing countries are invariably accompanied by large increases in contraceptive prevalence and in the annual number of new acceptors. This article applies a target-setting model to make hypothetical projections of trends in prevalence and number of acceptors over the course of a full fertility transition. The sensitivity of these trends to variations in proximate determinants such as the marriage pattern and the duration of lactational amenorrhea, as well as in the discontinuation rate and the method mix, are examined. It is concluded that a contraceptive prevalence of around 75 percent is needed to achieve replacement-level fertility and that variations in proximate determinants other than contraceptive prevalence have only a modest effect on this result. On the other hand, trends in new acceptors are demonstrated to be very sensitive to discontinuation rate changes. As a consequence, it is generally difficult to draw conclusions about trends in fertility from trends in acceptors.
发展中国家生育率的大幅下降总是伴随着避孕普及率和每年新采用避孕措施人数的大幅增加。本文应用一个目标设定模型，对整个生育率转变过程中避孕普及率和采用者人数的趋势进行假设预测。研究了这些趋势对诸如婚姻模式、哺乳期闭经持续时间等直接决定因素变化的敏感性，以及对停用率和避孕方法组合变化的敏感性。得出的结论是，要实现更替水平的生育率，避孕普及率需要达到约75%，并且除避孕普及率之外的直接决定因素的变化对这一结果只有适度影响。另一方面，新采用者的趋势被证明对停用率变化非常敏感。因此，一般很难从采用者的趋势中得出关于生育率趋势的结论。
