(375) Patient and county-level factors associated with trial of labor after cesarean access and success

Because trial of labor after cesarean (TOLAC) carries risks, ACOG recommends TOLAC be attempted in facilities able to respond to such risks, which may limit access at the county level. We sought to analyze patient and county-level factors associated with TOLAC access and VBAC success.

Study Design:

This is a retrospective cross-sectional study of county-identified US natality data from 2016-2021. Individuals with one prior cesarean birth and a liveborn singleton, cephalic, non-anomalous infant delivered between 39 and 42 weeks were included. Those with prior vaginal birth, diabetes, or chronic hypertension were excluded. TOLAC status was determined from the birth certificate. Overall TOLAC rates and VBAC rates among individuals who attempted TOLAC were calculated at the county level. Counties with TOLAC or VBAC rates in the top and bottom quartile were compared to each other. A patient-level logistic regression was used to identify patient and county-level factors associated with the primary outcomes. County-level factors of interest were obtained from the 2021 Area Health Resource Files and standardized using z-scores.

Results:

Of 809,969 eligible individuals, 168,574 (20.8%) attempted TOLAC. Of the 1,667 counties in the dataset, 1,409 (84.5%) reported at least one TOLAC. The median TOLAC rate was 12.2% [IQR: 3.1-22.5%]; there was significant geographic variation (Figure). Factors associated with counties with high TOLAC rates included: younger age, more education, lower BMI, urban settings, more Ob-Gyn providers and NICU beds, and lower unemployment rates (Table). The median VBAC rate was 60.4% [IQR: 46.6 – 70.6%]. Factors associated with lower rates of VBAC success included Black race, relatively smaller metropolitan area, fewer Ob-Gyn providers, and higher rates of uninsurance (Table).

Conclusion:
There is widespread variation in TOLAC access in the United States. Patient- and county-level factors associated with TOLAC access and VBAC success differ, which highlights potential disparities and limitations in access to care.