ObjectiveTo synthesise the evidence from studies that implemented interventions to increase/reintroduce the use of assisted vaginal births (AVB).DesignSystematic review.Eligibility criteriaWe included experimental, semi-experimental and observational studies that reported any intervention to reintroduce/increase AVB use.Data sourcesWe searched PubMed, EMBASE, CINAHL, LILACS, Scopus, Cochrane, WHO Library, Web of Science, ClinicalTrials.gov and WHO.int/ictrp through September 2021.Risk of biasFor trials, we used the Cochrane Effective Practice and Organisation of Care tool; for other designs we used Risk of Bias for Non-Randomised Studies of Interventions.Data extraction and synthesisDue to heterogeneity in interventions, we did not conduct meta-analyses. We present data descriptively, grouping studies according to settings: high-income countries (HICs) or low/middle-income countries (LMICs). We classified direction of intervention effects as (a) statistically significant increase or decrease, (b) no statistically significant change or (c) statistical significance not reported in primary study. We provide qualitative syntheses of the main barriers and enablers for success of the intervention.ResultsWe included 16 studies (10 from LMICs), mostly of low or moderate methodological quality, which described interventions with various components (eg, didactic sessions, simulation, hands-on training, guidelines, audit/feedback). All HICs studies described isolated initiatives to increase AVB use; 9/10 LMIC studies tested initiatives to increase AVB use as part of larger multicomponent interventions to improve maternal/perinatal healthcare. No study assessed women’s views or designed interventions using behavioural theories. Overall, interventions were less successful in LMICs than in HICs. Increase in AVB use was not associated with significant increase in adverse maternal or perinatal outcomes. The main barriers to the successful implementation of the initiatives were related to staff and hospital environment.ConclusionsThere is insufficient evidence to indicate which intervention, or combination of interventions, is more effective to safely increase AVB use. More research is needed, especially in LMICs, including studies that design interventions taking into account theories of behaviour change.PROSPERO registration numberCRD42020215224.