Background Information about the use of the findings of quality assessments in maternal and neonatal (MN) care is lacking and the development of tools capable to effectively address quality gaps is a key priority. Furthermore, little is known about factors that act as barriers or facilitators to change at facility level. Based on the extensive experience made with the WHO Quality Assessment and Improvement MN (QA/QI MN) tool, an overview is provided of the improvements in quality of care (QoC) which were obtained over time and of the factors influencing change. Methods All documented reports on the implementation of the WHO QA/QI MN tool were searched and screened for inclusion. Reports were considered if bringing evidence from both the baseline assessment and the reassessment. Changes were considered in four domains: maternal care, neonatal care, infrastructure and policies, with reference made to WHO maternal and neonatal care standards. The observed improvements were categorized according to intensity and extent across the sample of health facilities. Factors influencing change were categorized into internal and external and further classified as barriers or facilitators. Results. Changes were documented after an average period of 1.2 years from first assessment in 27 facilities belonging to 9 different countries in Central and Eastern Europe (3), Central Asia (3), sub-Saharan Africa (2) and Latin America (1). Improvements were observed in all areas of care but were greater and more frequently observed in areas related to appropriate case management and respectful care for both mothers and newborns. Although widespread across most facilities and countries, the observed improvements were not covering all the quality gaps observed at the baseline assessment nor were always sufficient to achieve standard care. Factors facilitating change as well as barriers were mainly related to the capacity of the managers and head of units to involve and motivate their staff members. Conclusions The use of WHO QA/QI MN tool proved effective in promoting significant changes in quality of care. The review of observed improvements and of factors influencing change at facility level shows that participatory assessment tools that promote a constructive dialogue with hospital managers and staff and support them in acquiring capacity in this role are crucial to implement effective quality cycles.