Epidemiologist, Ibis Reproductive Health, Oakland, CA.
Professor, Advancing New Standards in Reproductive Health (ANSIRH), Bixby Center for Global Reproductive Health, Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, University of California, San Francisco.
Perspect Sex Reprod Health. 2018 Mar;50(1):7-14. doi: 10.1363/psrh.12047. Epub 2018 Jan 12.
Nonuse and inconsistent use of contraceptives contribute to a high incidence of unintended pregnancy and abortion among U.S. women. Little is known, however, about how these outcomes shape women's subsequent contraceptive use and unintended pregnancy risk.
Contraceptive use was examined among 880 participants in the Turnaway Study, a five-year longitudinal study of women who sought abortions at 30 U.S. facilities in 2008-2010. Multivariable mixed-effects logistic and multinomial regression models assessed differences in use by whether women received the abortion; results were used to calculate predicted percentages of women using each method. The main groups of interest were 415 women who had an abortion at a gestation near their facility's limit and 160 who were denied abortion because they were beyond the limit, and who consequently gave birth.
During each of the approximately five years of follow-up, the predicted percentage using any contraceptive method was 86% among women who had the abortion and 81% among those denied it. Over the entire period, the former women were more likely than the latter to use any method (odds ratio, 1.8). However, they were less likely to rely on female sterilization, rather than no method (risk ratio, 0.5), and more likely to use barrier methods (1.7) or short-acting reversible contraceptives (2.6).
Women's elevated risk of unintended pregnancy after abortion is likely due at least partly to reliance on methods with relatively low effectiveness. Factors affecting contraceptive access postabortion, as well as individual characteristics such as fecundability, require research attention.
在美国，女性因未使用或未正确使用避孕药具而导致意外怀孕和人工流产的发生率很高。然而，人们对这些结果如何影响女性随后的避孕措施使用和意外怀孕风险知之甚少。
对 2008 年至 2010 年间在美国 30 家医疗机构寻求堕胎的 880 名参与者进行了避孕措施使用情况的调查。采用多变量混合效应逻辑回归和多项回归模型，根据女性是否接受堕胎，评估使用避孕措施的差异；结果用于计算每位女性使用每种方法的预测百分比。主要关注的两个群体是 415 名在设施妊娠限制附近进行堕胎的女性和 160 名因超过限制而被拒绝堕胎并随后分娩的女性。
在大约五年的随访期间，接受堕胎的女性中，任何避孕方法的预测使用率为 86%，而被拒绝堕胎的女性为 81%。在整个期间，前者比后者更有可能使用任何避孕方法（优势比为 1.8）。然而，她们更倾向于选择非手术避孕方法（风险比为 0.5），而不是不使用任何避孕方法，并且更倾向于使用屏障方法（1.7）或短期可逆避孕药具（2.6）。
女性堕胎后意外怀孕的风险增加可能至少部分归因于依赖避孕效果相对较低的方法。需要关注影响堕胎后避孕措施获取的因素，以及生育能力等个体特征。
