Intervention thresholds and cesarean section rates: A time-trends analysis.
To improve understanding of rising cesarean section (CS) rates in the UK, this study assessed the relation between clinician thresholds for performing CS for delayed labor progress or suspected fetal distress and corresponding CS rates in Aberdeen, UK. Time-trends analysis of term births from 1988 to 2012 in a population of nulliparous women (N = 53 745) in Aberdeen, UK, using Chi-square test for trend, and binary logistic regression. Data were obtained from the Aberdeen Maternity and Neonatal Databank. Unplanned CS rates per quintile increased from 11.0% (1391/12 686) to 21.1% (2383/11 273) between 1988 and 2012, while planned CS rates increased from 2.7% (338/12 686) to 5.2% (591/11 273). The median duration of labor before CS for delayed progress per quintile decreased from 17.2 (IQR 12.5-22.3) to 13.1 hours (9.6-16.9) before first stage CS and from 17.1 (12.6-22.3) to 15.3 (11.5-19.1) hours before second stage CS (P < .001). The proportion of CS for suspected fetal distress performed with evidence of fetal acidosis declined from 23.4% (98/418) to 17.4% (106/608) per quintile (P < .01). Neonatal unit admission (adjusted OR 1.99, 95% CI 1.85-2.14) was more likely following unplanned CS than vaginal births. Birth trauma was less likely following both unplanned (adjusted OR 0.48, 95% CI 0.39-0.60) and planned (adjusted OR 0.33, 95% CI 0.18-0.63) CS. Increased CS rates can be partly attributed to lowered clinical thresholds for intrapartum CS. Higher CS rates are associated with less birth trauma for the offspring.