An Intrapartum Cesarean Delivery Classification System - a prospective eighteen year longitudinal cohort study

There is no universal classification system for the indications for cesarean delivery. Separate standardized and comprehensive classification systems are needed for intrapartum and prelabor cesarean delivery.

This study aimed to describe the value of a standardized and comprehensive Intrapartum Cesarean Delivery Classification System (ICDCS) and its interaction with other labor and delivery events and outcomes within the Ten Group Classification System.

This prospective cohort study was conducted at an Irish tertiary maternity center. The study population was single cephalic pregnancies with spontaneous or induced labor at ≥ 37 weeks' gestation delivered over an 18 year period between January 1, 2005 and December 31, 2022. These groups included nulliparous women with a single cephalic fetus at 37 weeks' gestation or later, either in spontaneous labor (Group 1) or with induced labor (Group 2a), multiparous women (excluding those with previous cesarean delivery) with a single cephalic fetus at 37 weeks' gestation or later, either in spontaneous labor (Group 3) or with induced labor (Group 4a), and women with a previous cesarean delivery who have a single cephalic fetus at 37 weeks' gestation or later, either in spontaneous labor (Group 5a) or with induced labor (Group 5b). Each cesarean delivery performed after the onset of spontaneous labor or induction of labor was classified using the Intrapartum Cesarean Delivery Classification System and recorded in the National Maternity Hospital Annual Clinical Report together with other labor and delivery events and outcomes. The differences in proportions were assessed using chi-square tests, with a P value of < .05 considered significant.

Over 18 years, 151,284 women were delivered at the National Maternity Hospital, with a cesarean delivery rate of 24.5% (37,131/151,284). In Groups 1, 2a, 3, 4a, 5a and 5b, 13,124 intrapartum cesarean deliveries were performed and classified using the Intrapartum Cesarean Delivery Classification System. The cesarean delivery rate increased over the 18 year study period in Group 1 from 7.4% to 11.9% (P<.001) and in Group 2a from 27.9% to 38.3% (P<0.001). The cesarean rates in Groups 3, 4a, 5a and 5b remained relatively stable. The Intrapartum Cesarean Delivery Classification System showed generally consistent patterns of subgroup indications within Groups 1, 2a, 3, 4a, 5a and 5b (Ten Group Classification System) and consistent differences in subgroup patterns between Groups 1, 2a, 3, 4a, 5a and 5b thereby allowing any variations to be easily seen. In 2 cohorts of Group 1 (2010-2012) and (2020-2022), there were significant increases in the overall cesarean delivery rate from 8.0% to 10.2% (P<.001), in the cesarean delivery rate for fetal (no oxytocin) from 1.3% to 2.6% (P<.001), in the cesarean delivery rate for dystocia-inefficient uterine action-poor response from 0.9% to 2.1% (P<.001), in the cesarean delivery rate for dystocia-efficient uterine action-persistent malposition and cephalopelvic disproportion from 0.8% to 1.5% (P<.001) and a decrease in the cesarean delivery rate for dystocia-inefficient uterine action-inability to treat-overcontracting from 1.2% to 0.4% (P<.001). Simultaneously, there were significant increases in postpartum hemorrhage ≥1000 mL from 0.6% to 4.1% (P<.001), and the vaginal operative delivery rate from 24.9% to 29.0% (P<.001) but a decrease in the use of oxytocin from 52.6% to 48.0% (P<.001).

The Intrapartum Cesarean Delivery Classification System has been used successfully for 18 years. When the absolute incidences of indications were interpreted together with the absolute incidences of other labor events, outcomes, and processes within Groups 1, 2a, 3, 4a, 5a and 5b, clinical patterns emerged which depended on the intrapartum guidelines. The Intrapartum Cesarean Delivery Classification System in conjunction with the Ten Group Classification System, provides a more granular understanding of the labor events and outcomes allowing for potential improvements in intrapartum guidelines.