Unintended pregnancy is a global public health concern. However, the effect of contraceptive failure on unintended pregnancy remains unclear in Nigeria. We undertook a longitudinal analysis to examine the effect of contraceptive failure on unintended pregnancy among urban women in Nigeria. We used panel data from the Nigerian Urban Reproductive Health Initiative. The Measurement, Learning and Evaluation program conducted the surveys among a cohort of women aged 15–49 who were first interviewed at baseline in 2010/2011 and followed up at endline in 2014/2015. Analytic sample was 4140 women aged 15–49 who ever used contraceptives. We fitted three-level multilevel binary logistic regression models estimated with GLLAMM. The study established evidence that there is a significant effect of contraceptive failure on unintended pregnancy among urban women in Nigeria. The positive effect of between-person contraceptive failure indicates that respondents who experienced more contraceptive failure than the average in the sample had 5.26 times higher odds of unintended pregnancy (OR = 5.26; p-value < 0.001). Results also established a significant effect of within-person contraceptive failures among the respondents. Findings suggest there is evidence of a significant longitudinal effect of contraceptive failure on unintended pregnancy in urban Nigeria. Efforts to reduce unintended pregnancy must include interventions to address the problem of contraceptive failure among urban women in Nigeria.

意外怀孕是一个全球性的公共卫生问题。然而，在尼日利亚，避孕失败对意外怀孕的影响仍不清楚。我们进行了纵向分析，探讨避孕失败对尼日利亚城市妇女意外怀孕的影响。我们使用了尼日利亚城市生殖健康倡议的面板数据。测量、学习和评估计划对一组 15-49 岁的女性进行了调查，这些女性在 2010/2011 年首次接受了基线访谈，并在 2014/2015 年结束时进行了随访。分析样本为 4140 名曾经使用过避孕药具的 15-49 岁女性。我们拟合了用 GLLAMM 估计的三级多级二元逻辑回归模型。该研究证实，避孕失败对尼日利亚城市妇女的意外怀孕有显着影响。人与人之间避孕失败的积极影响表明，经历过更多避孕失败的受访者的意外怀孕几率比样本中平均水平高出 5.26 倍（OR = 5.26；p值 < 0.001）。结果还确定了受访者内部避孕失败的显着影响。研究结果表明，有证据表明，尼日利亚城市地区避孕失败对意外怀孕有显着的纵向影响。减少意外怀孕的努力必须包括采取干预措施解决尼日利亚城市妇女避孕失败的问题。