1. Epidural and spinal anesthesia use during labor: 27-state reporting area, 2008;Osterman;Natl Vital Stat Rep,2011
2. Contemporary patterns of spontaneous labor with normal neonatal outcomes;Zhang;Obstet Gynecol,2010
3. Epidural versus non-epidural or no analgesia for pain management in labour;Anim-Somuah;Cochrane Database Syst Rev,2018
4. Early versus late initiation of epidural analgesia for labour;Sng;Cochrane Database Syst Rev,2014
5. ACOG Practice Bulletin No. 209: Obstetric analgesia and anesthesia;Obstet Gynecol,2019