BACKGROUND: The United Nations' Sustainable Development Goals (SDGs) include reducing the global maternal mortality rate to less than 70 per 100,000 live births and ending preventable deaths of newborns and children under five years of age, in every country, by 2030. Maternal and perinatal death audit and review is widely recommended as an intervention to reduce maternal and perinatal mortality, and to improve quality of care, and could be key to attaining the SDGs. However, there is uncertainty over the most cost-effective way of auditing and reviewing deaths: community-based audit (verbal and social autopsy), facility-based audits (significant event analysis (SEA)) or a combination of both (confidential enquiry). OBJECTIVES: To assess the impact and cost-effectiveness of different types of death audits and reviews in reducing maternal, perinatal and child mortality. SEARCH METHODS: We searched the following from inception to 16 January 2019: CENTRAL, Ovid MEDLINE, Embase OvidSP, and five other databases. We identified ongoing studies using ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform, and searched reference lists of included articles. SELECTION CRITERIA: Cluster-randomised trials, cluster non-randomised trials, controlled before-and-after studies and interrupted time series studies of any form of death audit or review that involved reviewing individual cases of maternal, perinatal or child deaths, identifying avoidable factors, and making recommendations. To be included in the review, a study needed to report at least one of the following outcomes: perinatal mortality rate; stillbirth rate; neonatal mortality rate; mortality rate in children under five years of age or maternal mortality rate. DATA COLLECTION AND ANALYSIS: We used standard Cochrane Effective Practice and Organisation of Care (EPOC) group methodological procedures. Two review authors independently extracted data, assessed risk of bias and assessed the certainty of the evidence using GRADE. We planned to perform a meta-analysis using a random-effects model but included studies were not homogeneous enough to make pooling their results meaningful. MAIN RESULTS: We included two cluster-randomised trials. Both introduced death review and audit as part of a multicomponent intervention, and compared this to current care. The QUARITE study (QUAlity of care, RIsk management, and TEchnology) concerned maternal death reviews in hospitals in West Africa, which had very high maternal and perinatal mortality rates. In contrast, the OPERA trial studied perinatal morbidity/mortality conferences (MMCs) in maternity units in France, which already had very low perinatal mortality rates at baseline. The OPERA intervention in France started with an outreach visit to brief obstetricians, midwives and anaesthetists on the national guidelines on morbidity/mortality case management, and was followed by a series of perinatal MMCs. Half of the intervention units were randomised to receive additional support from a clinical psychologist during these meetings. The OPERA intervention may make little or no difference to overall perinatal mortality (low certainty evidence), however we are uncertain about the effect of the intervention on perinatal mortality related to suboptimal care (very low certainty evidence).The intervention probably reduces perinatal morbidity related to suboptimal care (unadjusted odds ratio (OR) 0.62, 95% confidence interval (CI) 0.40 to 0.95; 165,353 births; moderate-certainty evidence). The effect of the intervention on stillbirth rate, neonatal mortality, mortality rate in children under five years of age, maternal mortality or adverse effects was not reported. The QUARITE intervention in West Africa focused on training leaders of hospital obstetric teams using the ALARM (Advances in Labour And Risk Management) course, which included one day of training about conducting maternal death reviews. The leaders returned to their hospitals, established a multidisciplinary committee and started auditing maternal deaths, with the support of external facilitators. The intervention probably reduces inpatient maternal deaths (adjusted OR 0.85, 95% CI 0.73 to 0.98; 191,167 deliveries; moderate certainty evidence) and probably also reduces inpatient neonatal mortality within 24 hours following birth (adjusted OR 0.74, 95% CI 0.61 to 0.90; moderate certainty evidence). However, QUARITE probably makes little or no difference to the inpatient stillbirth rate (moderate certainty evidence) and may make little or no difference to the inpatient neonatal mortality rate after 24 hours, although the 95% confidence interval includes both benefit and harm (low certainty evidence). The QUARITE intervention probably increases the percent of women receiving high quality of care (OR 1.87, 95% CI 1.35 - 2.57, moderate-certainty evidence). The effect of the intervention on perinatal mortality, mortality rate in children under five years of age, or adverse effects was not reported. We did not find any studies that evaluated child death audit and review or community-based death reviews or costs. AUTHORS' CONCLUSIONS: A complex intervention including maternal death audit and review, as well as development of local leadership and training, probably reduces inpatient maternal mortality in low-income country district hospitals, and probably slightly improves quality of care. Perinatal death audit and review, as part of a complex intervention with training, probably improves quality of care, as measured by perinatal morbidity related to suboptimal care, in a high-income setting where mortality was already very low. The WHO recommends that maternal and perinatal death reviews should be conducted in all hospitals globally. However, conducting death reviews in isolation may not be sufficient to achieve the reductions in mortality observed in the QUARITE trial. This review suggests that maternal death audit and review may need to be implemented as part of an intervention package which also includes elements such as training of a leading doctor and midwife in each hospital, annual recertification, and quarterly outreach visits by external facilitators to provide supervision and mentorship. The same may also apply to perinatal and child death reviews. More operational research is needed on the most cost-effective ways of implementing maternal, perinatal and paediatric death reviews in low- and middle-income countries.