616 Impact of contemporary labor curves on primary cesarean delivery at a single institution

Abstract

In 2010, data was published that updated the expected duration of both the latent and active phase of labor in a contemporary group of women. Current professional society guidelines suggest that use of these new labor curves is an important component of reducing the primary cesarean delivery rate. The aim of this study was to assess whether there has been a reduction in primary cesarean delivery rates since adoption of these new guidelines. Retrospective cohort study of all women with term, vertex, non-anomalous, singleton pregnancies without a previa or history of a prior cesarean section at a single academic medical center between 2004-2019. The new labor curves were adopted into practice after 2010. Study years were grouped by four-year epochs. The Cochran-Armitage test for trend was used to assess for differences in primary cesarean delivery rates over time. A sub-analysis was performed for cesarean delivery indicated for arrest disorders stratified by arrest of dilation (cervix <10cm) and arrest of descent (cervix=10cm). There were 21,784 women with 3,653 (16.7%) primary cesarean deliveries included in the analysis. The overall primary cesarean rate increased from 14.7% in 2004-2007 to 17.7% in 2016-2019 (p<.001; Figure 1). Nulliparous patients had higher cesarean delivery rates over time (24.1 % vs 29.1%; p<.001) while rates among multiparous patients remained stable (6.8% vs 7.5%; p=.254). If cesarean was indicated for an arrest disorder, there were increased rates of cervix ≥5cm (79.9% vs 86.5%; p.010), but not cervix ≥6cm (68.4% vs 70.8%; p=.290) at the last exam before delivery. Overall, there was no change in cesarean delivery indicated for arrest of dilation (p=.442), but higher rates of arrest of descent (p=.016, Table 1). Operative vaginal delivery use decreased over time (5.9% vs 4.1%; p<.001). Since publication and adoption of contemporary labor curves, rates of term primary cesarean delivery have increased at our institution, specifically in nulliparous patients. Different strategies may be needed for improvement in primary cesarean delivery rates.View Large Image Figure ViewerDownload Hi-res image Download (PPT)