(1145) Gestational age variations in indications for primary cesarean delivery in very advanced maternal aged women

Objective: Pregnant patients of very advanced maternal age (vAMA, <45 years at delivery) are at increased risk for cesarean delivery (CD). Indications which have been known to significantly increase rates of primary cesarean delivery (PCD) in the general population are labor arrest, non-reassuring fetal status, and malpresentation. Trends in indications for PCD in the vAMA population have not been well elucidated nor is it known if trends vary by gestational age. We sought to determine indications for primary cesarean delivery in vAMA patients and compare differences by gestational age.

Study Design: Cohort study of pregnant individuals >45 years old delivering at a single institution between 2014-2021 (n = 432). Delivery information such as mode of delivery, history of previous cesarean delivery, and indication for PCD were collected. Chart review was performed to confirm the primary indication from the operative summary. Descriptive statistics were performed. Differences in indications for PCD between the term and preterm subgroups ( < 37 weeks and >37 weeks) were compared using chi square.

Results: Of 432 vAMA patients, 351 (81%) delivered by CD. Of these, 276 were PCDs (64%). The most common indication for PCD in this vAMA group was maternal request (24%) followed by multifetal gestation (15%) and arrest of dilation (14%). Analysis comparing indications between term and preterm subgroups revealed arrest of dilation and maternal request were more likely indications in the term group (p= 0.004, p = 0.001 respectively), whereas in the preterm group multifetal gestation was a more likely indication (p= < 0.0001).

Conclusion: The rate of primary cesarean delivery in the vAMA group is much higher than the national average (which was about 22% in 2020). The common indications for PCD in the vAMA population differ from those in the general population and appear to vary by gestational age. Initiatives to decrease PCD rates in centers with a large vAMA population may benefit from the perspective gained from this trend analysis.