Desired fertility is defined as the number of births a family would choose in a situation termed by demographers a "perfect contraceptive society", that is, one in which the family has access to a contraceptive technology with no economic costs and free of preference drawbacks.
Population and Economic Change in Developing Countries
By Richard A. Easterlin, Universities--National Bureau Committee for Economic Research
下一页提到实际生育率可以高于、低于、等于生育意愿；如果实际生育率低于生育意愿，那么说明存在有意的生育控制。
个人认为，在避孕措施完善的今天，绝大多数家庭可以按照自己的意愿完成生育控制。所以在很多没有强制计生的国家，生育率也那么低。
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