Objective The objective of this study was to assess caesarean section (CS) rates before and after the implementation of the Project Appropriate Birth (PPA), based on the Robson ten group classification system. Design A before‐and‐after study. Setting Maternity hospital in South Brazil. Population All pregnant women attending from April 2016 to April 2017 (period 1, pre‐implementation of PPA) and from June 2017 to June 2018 (period 2, post‐implementation of PPA). Methods Maternal and obstetric characteristics were evaluated, including Robson’s classification, based on the characteristics of pregnancy and childbirth. A chi‐square test and crude and adjusted relative rates were used to analyse the study variables. The significance level was set at 5%. Main outcome measures The CS rate for each group, their contribution to the overall CS rate and the differences in these contributions before and after PPA implementation. Results The CS rates decreased from 62.4 to 55.6%, which represented a 10.9% reduction after the implementation of the PPA. Pregnant women in Robson classification groups 1–4 had a 21.4% reduction in CS rates, ranging from 49.1 to 38.6%. The greatest contributors to the overall CS rates were group 5 and group 2, accounting for more than 60% of the CS deliveries. Conclusion The study results suggest that Project Appropriate Birth had an impact on the reduction of CS rates, especially in Robson classification groups 1 through 4, which indicates that providing mothers with evidence‐based interventions for labour and childbirth assistance contributed to reduce CS rates. Tweetable abstract The Project Appropriate Birth is an innovative project that has demonstrated promising results, suggesting that interventions based on scientific evidence can lead to real changes in childbirth care, contributing to reduce CS rates. The aim of the PPA is to promote activities to improve childbirth care and encourage vaginal delivery. In this study, 6238 pregnant women admitted to the hospital for delivery were included and classified into one of the Robson 10‐group classification. Findings revealed a 10.9% reduction in the overall CS rate and a 21.4% reduction for pregnant women in Robson classification groups 1 through 4, after the implementation of the PPA.