Contemporary Trends in Operative Vaginal Delivery and Obstetric Anal Sphincter Injuries from 2016-2023

Operative vaginal delivery (OVD) has experienced a decline, primarily driven by decreasing rates of forceps-assisted vaginal delivery (FAVD). FAVD rates have been suspected to be declining to a point where recovery of this skill may be improbable. While there are numerous reasons for this decline ranging from lack of training to patient preferences, the same period has been suspected to have worsening morbidity with FAVD. Concerns have been raised with respect to obstetric anal sphincter injuries (OASIS). To characterize national trends in OVD and risk factors for associated OASIS between 2016 and 2023, assessing changes in OVD utilization and the associated risk of OASIS.

This is a cross-sectional study using National Vital Statistics System birth certificate data between 2016 to 2023 to identify temporal trends in OVD and OASIS rates. Liveborn deliveries undergoing trial of labor from 34 weeks and 0 days to 42 weeks and 6 days to patients aged 16-50 years of age were included. Pregnancies with multifetal gestations, fetal anomalies, non-vertex presentations, and unknown mode of delivery were excluded. Temporal trends in OVD and OASIS were assessed using Joinpoint regression. Multivariable logistic regression models were fit to assess the association between OASIS and OVD, adjusting for maternal demographics and comorbidities.

Of the 21,191,398 liveborn deliveries identified, 18,054,141 (85.2%) were spontaneous vaginal births, 2,303,168 (10.9%) were cesarean after trial of labor, 136,927 (0.6%) were forceps-assisted vaginal deliveries (FAVD), and 697,162 (3.3%) were vacuum-assisted vaginal deliveries (VAVD) with a OVD composite of 3.9%. OVD rates decreased significantly from 4.6% to 4.1% (annual average percent change (AAPC): -1.6%, 95% CI: -1.9% to -1.4%). Specifically, FAVD rates declined from 0.8% to 0.6% (AAPC: -3.1%, 95% CI: -3.7% to -2.6%) and VAVD rates declined from 3.8% to 3.4% (AAPC -1.4%, 95%CI: -1.7% to 1.1%). OASIS rates in the overall group did not significantly change (AAPC 1.4%, 95%CI: -2.1% to 4.4%), although among FAVD, there was a significant increase in rates of OASIS from 9.3% in 2016 to 14.0% in 2023 (AAPC 4.8%, 95%CI: 2.3% to 7.0%). Adjusted multivariable logistic regression noted higher likelihood of OASIS in FAVD (aOR 9.50, 95%CI: 9.33 to 9.66), and VAVD (aOR 3.90, 95%CI: 3.85 to 3.94) when compared to spontaneous vaginal birth, adjusting for maternal age, maternal BMI, and maternal comorbidities including diabetes and hypertensive disorders.

The primary finding in this study was a national decline in OVD with significantly greater declines in FAVD and an increasing rate of OASIS among FAVD. Whether targeted interventions to enhance training in safe FAVD may increase proficiency in this technique remains to be seen.