Women will have the initial slow-release Dinoprostone pessary removed followed by insertion of quick-release Dinoprostone tablet (Prostin® 3 mg Dinoprostone vaginal tablet; Pfizer, UK) high in the posterior vaginal fornix immediately after removal of the slow-release pessary. The tablet will be left for 6 hours followed by vaginal reassessment and insertion of a second tablet if ARM is still not achievable.