Does the Decision to Perform Cesarean Delivery for Nonreassuring Fetal Status Vary by Time of Day? [ID: 1376814]

INTRODUCTION: Nonreassuring fetal status (NRFS) is a diagnosis lacking standardized definitions, making the diagnosis susceptible to bias and systemic factors. We assessed whether the decision to proceed with intrapartum cesarean delivery (CD) was associated with time of the day and whether this relationship was influenced by the presence of in-house obstetricians. METHODS: This was a retrospective cohort study of term pregnancies admitted in spontaneous labor or for induction between January 2019 and June 2021. The primary outcome was decision to perform intrapartum CD for NRFS. Generalized additive models with smoothing splines were used to explore nonlinear associations between time of day and CD rates. Results were then stratified by whether the attending obstetrician was in-house or remote. RESULTS: Of 5,526 deliveries, 6.0% were intrapartum CD for NRFS. In the overall cohort, CD for NRFS was consistent throughout the day (P=.056). For patients with in-house obstetricians, the decision for CD for NRFS was not influenced by time of day (P=.072). For patients without in-house obstetricians, the decision to perform CD for NRFS was influenced by the time of day (P=.028), with a decreasing frequency from midnight to afternoon with nadir at 15:00 (2.5%), and a subsequent increasing frequency that peaked at 23:00 (10.3%). CONCLUSION: The decision to perform CD for NRFS is influenced by the time of day when the obstetrician is not in-house. This decision is not affected by time of day when the obstetrician is in-house. Systemic factors such as immediate obstetrician availability affect the diagnosis of NRFS.