The desire to avoid pregnancy—to delay the next birth or have no further births—is a fundamental sexual and reproductive health indicator. We show that two readily available measures—prospective fertility preferences and the demand for contraception [Demand] construct—provide substantially different portraits of historical trends. They also yield correspondingly different assessments of the sources of contraceptive change. We argue, with supporting empirical evidence, that Demand enormously overstates the historical trend in the desire to avoid pregnancy because Demand as currently constructed is in part a function of contraceptive prevalence. This makes for “reverse causality” in decompositions of contraceptive change, producing an upward distortion on the order of 25 percentage points in the amount of contraceptive change attributed to a change in fertility desires. Decomposition of contraception change free of the distortion reveals that contraceptive change has been due almost entirely to more complete implementation of fertility preferences. This is explained in part by the surprisingly slight historical change in preferences, a fact we document and then show is a consequence of a historical shift in parity composition toward lower parities.

中文翻译：

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评估避免怀孕的愿望趋势：警示


避免怀孕的愿望——推迟下一次生育或不再生育——是一个基本的性和生殖健康指标。我们表明，两个现成的指标——预期生育偏好和避孕需求 [Demand] 结构——提供了截然不同的历史趋势画像。它们还对避孕变化的来源进行了相应的不同评估。我们凭借支持性的经验证据认为，需求极大地夸大了避免怀孕愿望的历史趋势，因为目前构建的需求在一定程度上是避孕药具普及率的函数。这使得避孕药具变化的分解存在“反向因果关系”，导致生育欲望变化的避孕药具变化量向上扭曲了 25 个百分点。没有扭曲的避孕变化的分解表明，避孕变化几乎完全是由于更完全地实施了生育偏好。这在一定程度上是由于偏好历史上出人意料的微小变化，我们记录并随后表明这一事实是平价构成向较低平价的历史转变的结果。