Main Findings
Our goal was to evaluate the contribution that cesarean performed without attempting vaginal birth (pre-labor cesarean) makes to all cesarean births, and to cesarean births within subgroups of the pregnant population. In our population, almost two-thirds of all cesareansand approximately 1 in 5 of all births were performed without attempting vaginal birth. Pre-labor cesareans also constituted 1 in 7 cesareans in the NTSV population, the standard metric for monitoring primary cesarean birth rates in the US. These pre-labor cesareans are invisible when reported within the NTSV cesarean metric.
The Robson classification highlighted patient groups where the contribution of pre-labor was especially high, including multiple pregnancies and singleton term cephalic pregnancies with a previous cesarean. This was true even in apparently more favorable clinical situations: only half of twins with twin A in a cephalic presentation, and 1/3 of singleton term cephalic pregnancies with one previous cesarean, attempted vaginal birth.
Cesarean without attempting vaginal birth also constituted 39.3% of allprimary cesarean births in our study (58.7% of cesareans in multiparous women with no history of cesarean and 32.4% of primary cesareans in nulliparous women), a contribution that has been largely unappreciated.
We were particularly interested in examining the rate and indications for pre-labor cesarean in singleton term cephalic pregnancies with no history of cesarean birth (Robson groups 1-4) compared to recently reported US national data.3 In our data, pre-labor cesareans constituted 20% of cesarean births in Robson groups 1-4. However, these pre-labor cesareans represented only 6.6% of all cesareans in our study population, much lower than the 27% contribution suggested in the study by Hehir et al.3 Suspected macrosomia and maternal request were the most common indications for primary pre-labor cesarean birth in singleton term cephalic pregnancies, these indications jointly accounting for almost half of cases. Notably, more than ¾ of the pre-labor cesareans performed due to suspected macrosomia were associated with an actual birth weight of <4500g.