Evaluation of cesarean delivery rates across Ontario from 2012-2019 using the modified Robson classification system: a population-based study.

Objective: This study aimed to describe the trends in cesarean delivery (CD) rates in Ontario using the modified Robson classification system and identify the most common indications for CD.

Methods: We conducted a population-based retrospective cross-sectional study using data from the Better Outcomes Registry & Network (BORN), a comprehensive maternal-child registry in Ontario. The analysis included all pregnant individuals who delivered a live or stillborn infant weighing ≥500 grams at ≥20 weeks' gestation between 1 April 2012 and 31 March 2019.

Results: A total of 952 567 pregnant individuals gave birth in Ontario, Canada, during the study period. Our findings demonstrated a slight increase in the overall CD rate over seven fiscal years from 2012-2013 to 2018-2019. Robson Group 5 (term singleton cephalic pregnancy with previous CD), Groups 1 and 2 (nulliparous, term, singleton, cephalic pregnancy and no labour, induced labour, or spontaneous labour), and Group 6 (nulliparous pregnancy with breech presentation) made the largest contributions to the overall CD rate over the study period. The top five primary indications for CD across all years included previous CD, atypical or abnormal fetal surveillance, malposition/malpresentation, non-progressive first stage of labour and non-progressive second stage of labour.

Conclusion: The results enhance our understanding of the key drivers of the CD rates. These findings will help to inform practice improvement, support policy change, and identify areas where future research is needed.