(498) Association of shift complexity and volume with cesarean delivery among nulliparous, term, singleton, vertex patients

: Studies have demonstrated high variability in obstetric outcomes between hospitals, but less is known about the effect of individual shift characteristics within a given hospital. We evaluated the association between obstetric unit shift characteristics (including volume and patient complexity) and cesarean delivery rate among nulliparous, term, singleton, vertex (NTSV) patients.

Study Design: This retrospective cohort study evaluated all NTSV pregnancies delivering at 7 hospitals within a large academic health system in New York from 2019-2022. Individual 12-hour nursing shifts were characterized based on delivery volume, patient complexity, night/day, and weekday/weekend. Individual patient clinical and sociodemographic factors were also evaluated. Maternal comorbidity burden was assessed by the Obstetric Comorbidity Index (OB-CMI) score. Shift volume for each obstetric unit was classified into three categories based on delivery volume quartile: low (1st quartile), medium (2nd and 3rd quartile), and high (4th quartile). Shift complexity for each obstetric unit was classified as low complexity (1st, 2nd, or 3rd quartile) or high complexity (4th quartile) based on median OB-CMI score of the patients delivering during the shift. The primary outcome was CD. Multivariable logistic regression was used to evaluate the association between shift characteristics and CD, adjusting for potential confounders.

Results: 38,114 subjects were included in the study. The overall rate of CD was 29.3% (n=11,159). Patients that delivered on a weekend or overnight shift were more likely to deliver vaginally (Table).  There was no difference in the rate of CD based on shift complexity or volume. Patients with higher OB-CMI scores, and those who self-identified as Asian or Pacific Islander, Hispanic, non-Hispanic Black, and multiracial/other were more likely to deliver via CD.

Conclusion: NTSV patients are more likely to deliver vaginally on weekend and overnight shifts. Shift volume or complexity are not associated with this outcome.