Injectables are one of the most popular methods of contraception worldwide, particularly in sub-Saharan Africa. An advantage of injectables over shorter-acting methods is that they provide additional flexibility by not requiring re-supply as frequently. However, there is a risk that injectable users may delay their next injection and may therefore have reduced or no protection from pregnancy. In surveys, women may report that they are using contraception in the form of injectables when the time since they had their last injection (more than four months) would imply that they have reduced protection against the risk of pregnancy. We carried out two field studies in urban Malawi, and we record reported injectable contraceptive use while also asking the number of months since women received their last injection. We observe that 13.8 percent of women who report using injectables also report that they received their last injection more than four months ago, and 11 percent report that they received their last injection more than six months ago. Our analysis highlights the need for additional follow-up with women who report using injectables in surveys to confirm whether they are, in fact, using the method effectively.

中文翻译：

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自上次注射后几个月内调整注射避孕药的使用

注射剂是全世界最流行的避孕方法之一，特别是在撒哈拉以南非洲地区。与短效方法相比，注射剂的一个优点是，它们不需要频繁地重新供应，从而提供了额外的灵活性。然而，注射使用者可能会推迟下次注射，因此可能会降低或没有怀孕保护。在调查中，女性可能会报告说，她们正在使用注射剂形式的避孕措施，而自上次注射以来的时间（超过四个月）意味着她们对怀孕风险的保护有所降低。我们在马拉维城市进行了两项实地研究，记录了注射避孕药具的使用情况，同时询问了妇女上次注射后的月数。我们观察到，13.8% 的自称使用注射剂的女性还表示，她们最后一次注射是在四个多月前，11% 的女性表示她们最后一次注射是在六个多月前。我们的分析强调，需要对在调查中报告使用注射剂的女性进行额外的随访，以确认她们是否确实有效地使用了该方法。