Rackin Heather M, Morgan S Philip
Department of Sociology, Louisiana State University, Baton Rouge, USA.
Carolina Population Center, Chapel Hill, USA.
Demogr Res. 2018 Jul-Dec;39:61-94. doi: 10.4054/DemRes.2018.39.3. Epub 2018 Jul 6.
Unwanted fertility is the key concept necessary to assess the potential impact of more perfect fertility control. Measuring this continues to be a significant challenge, with several plausible competing measurement strategies. Retrospective strategies ask respondents, either during pregnancy or after birth, to recall if they wanted a(nother) birth at conception; these reports are likely to be biased by an unwillingness to label a pregnancy or birth as unwanted (rationalization bias). Prospective strategies avoid this bias by questioning respondents prior to pregnancy, but reports are obtained months or years before pregnancy and so may not accurately reflect wantedness at conception.
We describe systematic errors associated with each strategy, show correspondence between strategies, and examine predictors of inconsistency.
Using the 1979 National Longitudinal Survey of Youth, we compare retrospective and prospective reports for 6,495 births from 3,578 women.
The prospective strategy produces a higher percentage of unwanted births than the retrospective strategy. But the two reports of wantedness are strongly associated - especially for the second birth (vs. other births) and for women with stable (vs. unstable) expectation patterns. Nevertheless, discordant reports are common and are predicted by women's characteristics.
Retrospective measures are biased by rationalization; prospective measures are biased when women change their expectations prior to conception. For practical and theoretical reasons, we argue that retrospective measurement is more promising for assessing wantedness.
We highlight shortcomings in both approaches. Demographers may find ways to measure wantedness more accurately, but many of the measurement problems seem intractable.
意外生育是评估更完善的生育控制潜在影响所需的关键概念。对此进行测量仍然是一项重大挑战，存在几种看似合理的相互竞争的测量策略。回顾性策略要求受访者在怀孕期间或分娩后回忆他们在受孕时是否想要（另一个）孩子；这些报告可能会因不愿意将怀孕或分娩标记为意外（合理化偏差）而产生偏差。前瞻性策略通过在怀孕前询问受访者来避免这种偏差，但报告是在怀孕前几个月或几年获得的，因此可能无法准确反映受孕时的意愿。
我们描述与每种策略相关的系统误差，展示策略之间的对应关系，并研究不一致性的预测因素。
利用1979年全国青年纵向调查，我们比较了3578名女性的6495次分娩的回顾性和前瞻性报告。
前瞻性策略产生的意外分娩百分比高于回顾性策略。但关于生育意愿的两种报告密切相关——尤其是对于第二胎（与其他胎次相比）以及期望模式稳定（与不稳定相比）的女性。然而，不一致的报告很常见，并且可以由女性特征预测。
回顾性测量因合理化而存在偏差；当女性在受孕前改变期望时，前瞻性测量存在偏差。出于实际和理论原因，我们认为回顾性测量在评估生育意愿方面更有前景。
我们强调了两种方法的缺点。人口统计学家可能会找到更准确测量生育意愿的方法，但许多测量问题似乎难以解决。
