Abstract：
Clinical guidelines for progestin-only pills (POPs) state that each pill should be taken at the same time each day, with only a \"three-hour window\" of tolerance before back-up contraception should be used. In this commentary, we summarize studies examining the timing of ingestion and mechanisms of action for various POP formulations and dosages. We found that different progestins have different properties that determine the effect of delayed or missed pills on effectiveness at preventing pregnancy. Our findings highlight that there is more margin for error for some POPs than guidelines suggest. The three-hour window recommendation should be re-evaluated in light of these findings. Since clinicians, potential POP users, and regulatory bodies rely on current guidelines to make decisions about POP use, a critical evaluation and update of these guidelines are urgently needed.
摘要：
仅含孕激素的药丸（POPs）的临床指南指出，每颗药丸应每天同时服用。在备用避孕之前，只有一个“三小时的耐受性窗口”。在这篇评论中，我们总结了研究各种POP制剂和剂量的摄入时机和作用机制的研究。我们发现不同的孕激素具有不同的特性，这些特性决定了延迟或错过的药丸对预防怀孕的有效性的影响。我们的发现强调，某些持久性有机污染物的错误余地比指南建议的要大。应根据这些发现重新评估三小时窗口建议。由于临床医生，潜在的POP用户，和监管机构依靠当前的指导方针来做出关于持久性有机污染物使用的决定，迫切需要对这些指南进行严格的评估和更新。
