School of Public Health, University of California, Berkeley, CA 94704, USA
Public Health & Planning, Policy and Design, University of California, Irvine, CA 92697, USA.
Hum Reprod. 2016 May;31(5):1113-9. doi: 10.1093/humrep/dew031. Epub 2016 Mar 9.
Does the incidence of spontaneous abortion correlate positively over conception cohorts with the incidence of non-clinically indicated induced abortion as predicted by shared risk aversion?
We find that the number of spontaneous and non-clinically indicated induced abortions correlates in conception cohorts, suggesting that risk aversion affects both the conscious and non-conscious mechanisms that control parturition.
Much literature speculates that natural selection conserved risk aversion because the trait enhanced Darwinian fitness. Risk aversion, moreover, supposedly influences all decisions including those that individuals can and cannot report making. We argue that these circumstances, if real, would manifest in conscious and non-conscious decisions to invest in prospective offspring, and therefore affect incidence of induced and spontaneous abortion over time.
STUDY DESIGN, SIZE, DURATION: Using data from Denmark, we test the hypothesis that monthly conception cohorts yielding unexpectedly many non-clinically indicated induced abortions also yield unexpectedly many spontaneous abortions. The 180 month test period (January 1995 through December 2009), yielded 1 351 800 gestations including 156 780 spontaneous as well as 233 280 induced abortions 9100 of which were clinically indicated.
PARTICIPANTS/MATERIALS, SETTING, METHODS: We use Box-Jenkins transfer functions to adjust the incidence of spontaneous and non-clinically indicated induced abortions for autocorrelation (including seasonality), cohort size, and fetal as well as gestational anomalies over the 180-month test period. We use cross-correlation to test our hypothesized association.
We find a positive association between spontaneous and non-clinically indicated induced abortions. This suggests, consistent with our theory, that mothers of conception cohorts that yielded more spontaneous abortions than expected opted more frequently than expected for non-clinically indicated induced abortion.
LIMITATIONS, REASONS FOR CAUTION: Limitations of our work include that even the world's best registration system will not capture all spontaneous abortions and that results may not generalize beyond Denmark.
Our findings imply that abortion, intentional or 'spontaneous,' follows from a woman's estimate, made consciously or otherwise, of the costs and benefits of extending gestation given characteristics of the prospective offspring, likely environmental circumstances at birth, and maternal resources.
STUDY FUNDING/COMPETING INTERESTS: The Robert Wood Johnson Health and Society Scholars Program funded the research described in this manuscript. None of the authors has any conflict of interest to declare.
自发流产的发生率是否与根据共同风险厌恶预测的非临床指征性人工流产的发生率呈正相关？
我们发现，自发流产和非临床指征性人工流产的数量在受孕队列中存在相关性，这表明风险厌恶会影响控制分娩的有意识和无意识机制。
大量文献推测，自然选择保留了风险厌恶，因为这种特征增强了达尔文适应性。此外，风险厌恶据说会影响个人能够和不能报告做出的所有决策。我们认为，如果这些情况确实存在，它们将表现在有意识和无意识的决定中，即在预期后代中进行投资，因此会影响随时间推移的人工流产和自然流产的发生率。
研究设计、规模、持续时间：使用丹麦的数据，我们检验了这样一个假设，即每月受孕队列中出现意外的大量非临床指征性人工流产也会出现意外的大量自发流产。180 个月的测试期（1995 年 1 月至 2009 年 12 月）产生了 1351800 次妊娠，包括 156780 次自然流产和 233280 次人工流产，其中 9100 次为临床指征性。
参与者/材料、设置、方法：我们使用 Box-Jenkins 传递函数来调整自发和非临床指征性人工流产的发生率，以适应 180 个月测试期内的自相关（包括季节性）、队列大小以及胎儿和妊娠异常。我们使用互相关来检验我们假设的关联。
我们发现自发流产和非临床指征性人工流产之间存在正相关。这表明，与我们的理论一致，在自发流产比预期多的受孕队列中，母亲选择非临床指征性人工流产的频率比预期的要高。
局限性、谨慎的原因：我们工作的局限性包括，即使是世界上最好的登记系统也无法捕捉到所有的自然流产，而且结果可能无法推广到丹麦以外。
我们的研究结果表明，堕胎，无论是故意的还是“自发的”，都源于女性对延长妊娠的成本和收益的估计，这是基于对预期后代的特征、出生时可能的环境情况以及母亲资源的有意识或无意识的评估。
研究资金/利益冲突：罗伯特·伍德·约翰逊健康与社会学者计划为本文所述的研究提供资金。作者均无利益冲突声明。
