(926) The Impact of Certified Nurse Midwife Presence on Cesarean Delivery Rates During Night Shifts

To determine whether cesarean delivery (CD)  rates vary by whether or not a certified nurse midwife (CNM) is present during labor and delivery night shifts. 

Study Design:

This was a retrospective cohort study at an academic hospital between 2017 and 2021 where all patients are cared for by a single team of 3 providers, with CNMs as part of the care team for  some, but not, all shifts.  Primary CD rates among nulliparous, term, singleton, vertex  (NTSV) pregnancies delivering on the night shift (7pm – 7am) were compared between shifts with only MD providers to shifts with both MDs and CNMs.  Additionally, rates of vaginal birth after cesarean (VBAC) in women undergoing a trial of labor were compared in the two types of shifts. Scheduled CD were excluded.  Statistical analysis was performed with χ2  tests for categorical variables and 2-sample t-test for continuous variables.  Logistic regression was performed to control for calendar year (as a marker for secular trends in CD rates and changes in patient demographics) but since CNM shifts were assigned randomly without consideration for patient factors, no further adjustment was required. 

Results:

There were 3281 NTSV pregnancies and 411 patients with prior CD attempting TOLAC.  CNMs were present for 70.1% of shifts.  For NTSV pregnancies, the CD rate during shifts with only MD providers was 18.8% compared to 19.4% in shifts with both MD and CNM providers (p=0.727). The VBAC rate was 43.5% in shifts with MD providers only compared to 57.0% in shifts with both CNMs and MDs, which was statistically significant (p= 0.015).  Logistic regression controlling for calendar year did not change the results for NTSV CD (OR 0.99, 95% CI 0.82 – 1.12) but did affect the standard error for VBAC rates (OR 1.4, 95% 0.95 – 2.22).

Conclusion:

The presence of CNM providers on a labor and delivery night shift was not associated with any difference in NTSV CD rates.  There did appear to be an association with increased VBAC rate, although this may be somewhat explained by confounders.