Obstetric interventions, trends, and drivers of change: A 20-year population-based study from Iceland.

BACKGROUND: Population data on obstetric interventions is often limited to cesarean delivery. We aimed to provide a more comprehensive overview of trends in use of several common obstetric interventions over the past 2 decades. METHODS: The study was based on nationwide data from the Icelandic Medical Birth Register. Incidence of labor induction, epidural analgesia, cesarean, and instrumental delivery was calculated for all births in 1995-2014. Change over time was expressed as relative risk (RR), using Poisson regression with 95% confidence intervals (CI) adjusted for several maternal and pregnancy-related characteristics. Analyses were stratified by women's parity and diagnosis of diabetes or hypertensive disorder. RESULTS: During the study period, there were 81 389 intended vaginal births and 5544 elective cesarean deliveries. Among both primiparous and multiparous women, we observed a marked increase across time for labor induction (RR 1.78 [CI 1.67-1.91] and RR 1.83 [CI 1.73-1.93], respectively) and epidural analgesia (RR 1.40 [CI 1.36-1.45] and RR 1.74 [CI 1.66-1.83], respectively). A similar trend of smaller magnitude was observed among women with hypertensive disorders but no time trend was observed among women with diabetes. Incidence of cesarean and instrumental delivery remained stable across time. DISCUSSION: The use of labor induction and epidural analgesia increased considerably over time, while the cesarean delivery rate remained low and stable. Increases in labor induction and epidural analgesia were most pronounced for women without a diagnosis of diabetes or hypertensive disorder and were not explained by maternal characteristics such as advanced age.