Using linked data to explore medical complications associated with Robson classification of cesarean deliveries in...

Cesarean delivery rates in the United States far exceed the World Health Organization (WHO)'s recommended population cesarean rate of 15%. This has resulted in calls from experts to reduce cesarean delivery rates. However, crude cesarean delivery rates are not necessarily comparable across populations since different birthing populations have different distributions of underlying cesarean delivery risk factors. WHO recommends using the Robson classification system to compare standardized cesarean delivery rates across populations, though it has been rarely used within the U.S.

The objectives of this study were to understand the distribution of cesarean deliveries using the Robson Classification system and to identify associated conditions (and potential drivers) of cesarean delivery across Robson groups.

Our data comes from the Pregnancy and Early Life Longitudinal Data System from the Massachusetts Department of Health, which contains all birth certificate records for Massachusetts from 2011 to 2018. Using the WHO Robson Classification System Implementation guide, we categorized births into one of its 10 categories based on data from birth certificate records and ICD-9 and ICD-10 codes from billing records. Using the linked birth certificate records and hospital discharge records we went beyond the Robson classifications and examined patterns in maternal comorbidities and labor and delivery complications of cesarean deliveries across Robson groups.

Among the 25% of birthing people who had singleton, term, vertex births with spontaneous labor, the cesarean delivery rate was 15% for nulliparous and 3% for multiparous (with no prior cesarean). The prevalence of maternal risk factors was 28% in the former and 30% in the latter. Labor and delivery complications were present in 46% and 35% of births, respectively. Birthing people with breech or transverse fetal presentation had the highest cesarean delivery rates around 95%. Multiparous birthing people with a prior cesarean delivery and cephalic, singleton, term births were the largest contributor to the cesarean delivery rate (38% of all cesareans). Almost all births for malpresentation or malposition of fetus had at least one labor and delivery complication but much lower rates of risk factors (between 25% and 46%).

While cesarean delivery rates, maternal risk factors, and labor and delivery complications followed similar patterns across Robson groups, there were notable discrepancies, especially in births with noncephalic presentations where maternal comorbidity rates matched lower cesarean-risk groups like the nulliparous single-term cephalic births.