RESUMEN
INTRODUCTION: Off-label use of the prostaglandin-E1 analogue misoprostol has become standard practice when inducing labour. In Denmark, a low-dosage misoprostol regimen is common. The regimen consists of one 25 µg application on the first day of induction. The registered prostaglandin-E2 analogue dinoprostone is used in 3 and 6 mg doses. This study compared induction procedures with dinoprostone and misoprostol in terms of induction time, foetal outcome and maternal outcome. MATERIAL AND METHODS: This retrospective study included 1,645 induced deliveries from two periods: 2003-2005, when dinoprostone was standard treatment (n = 635), and 2008-2010, when misoprostol was standard treatment (n = 633). We evaluated the induction method, outcomes and confounders using Kaplan-Meier, Cox and logistic regression analyses. RESULTS: In the first 24 h, 38% and 59% of women delivered in the misoprostol and dinoprostone groups, respectively. Compared with dinoprostone, misoprostol was associated with a longer induction time (hazard ratio = 0.79, 95% confidence interval (CI): 0.69-0.90). Both regimens showed similar risks of caesarean section (odds ratio (OR) = 0.88, 95% CI: 0.64-1.12), rates of meconium-stained amniotic fluid (OR = 0.85, 95% CI: 0.63-1.15), 5-min Apgar scores < 7 (OR = 1.73, 95% CI: 0.34-8.75), and transfers to neonatal intensive care units (OR = 0.64, 95% CI: 0.38-1.08). CONCLUSION: Low-dosage misoprostol required more time than dinoprostone to induce labour, but the two drugs were equally safe in terms of the risk of caesarean section and foetal outcomes. FUNDING: The Danish Ministry of Research and Innovation (#10-093833). TRIAL REGISTRATION: The Danish Data Protection Agency (#2011-41-5794).