Definitions of failed induction of labor in the literature: a systematic review

BACKGROUND: Induction of labor is a common obstetric intervention with rates up to 25% in developed countries. However, no accepted definition of failed induction of labor exists today. This challenges the comparability between studies investigating induction regimens in terms of efficacy and outcomes, thereby limiting the ability to generate homogenous and valid meta-analyses to inform practice. OBJECTIVE: The objective of this systematic review was to describe the definitions of failed induction of labor in the reported literature. METHODS: A systematic search was conducted in PudMed, EMBASE, and CINAHL. Randomized controlled trials and cohort studies, which explicitly stated a definition of failed induction of labor were included. We extracted the definition from each study and described the components of the definitions. RESULTS: A total of 96 studies were included, yielding 112 distinct definitions, the vast majority of which differed from one another. Significant heterogeneity was observed among these definitions, and twelve unique components were identified within them. The most frequently cited component was the duration of induction, appearing in 65% of the definitions. . CONCLUSION: The variation in definitions of failed induction of labor used in the literature is vast. To ensure consensus and increase comparability when comparing studies investigating induction of labor, a standard definition is highly needed. TRIAL REGISTRATION: Prior to this review a protocol was made and published on PROSPERO with ID number CRD42023405953.