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OBJECTIVE: To determine incidence and patient characteristics of women with uterine rupture during singleton births at term without a previous caesarean delivery.STUDY DESIGN: Population based cohort study. Women with term singleton birth, no record of previous caesarean delivery and planned vaginal delivery (n=611,803) were identified in the Danish Medical Birth Registry (1997-2008). Medical records from women recorded with uterine rupture during labour were reviewed to ascertain events of complete uterine rupture. Relative Risk (RR) and adjusted Relative Risk Ratio (aRR) of complete uterine rupture with 95% confidence intervals (95% CI) were ascertained according to characteristics of the women and of the delivery.RESULTS: We identified 20 cases with complete uterine rupture. The incidence of complete uterine rupture among women without previous caesarean delivery was about 3.3/100,000 deliveries. Multiparity (RR 8.99 (95% CI 1.86-43.29)), induction of labour (RR 3.26 (95% CI 1.24-8.57)), epidural analgesia (RR 10.78 (95% CI 4.25-27.39)), and augmentation by oxytocin (RR 9.50 (95% CI 3.15-28.63)) were associated with uterine rupture. Induction of labour was not significantly related to uterine rupture when adjusted for parity, epidural analgesia and augmentation by oxytocin.CONCLUSION: Although uterine rupture is rare, its association with epidural analgesia and augmentation of labour with oxytocin in multipara should be considered. Thus, vigilance should be exercised when labour is obstructed and there is need for epidural analgesia and/or augmentation by oxytocin in multiparous women. Due to the rare occurrence of uterine rupture caution should be exerted when interpreting the findings of this study.

BACKGROUND: Variation in birth registration criteria may compromise international comparisons of fetal and infant mortality. We examined the effect of birth registration practices on fetal and infant mortality rates to determine whether observed differences in perinatal and infant mortality rates were artifacts of birth registration or reflected true differences in health status.METHODS: A retrospective population-based cohort study was done using data from Canada, United States, Denmark, Finland, Iceland, Norway, and Sweden from 1995-2005. Main outcome measures included live births by gestational age and birth weight; gestational age-and birth weight-specific stillbirth rates; neonatal, post-neonatal, and cause-specific infant mortality.RESULTS: Proportion of live births <22 weeks varied substantially: Sweden (not reported), Iceland (0.00%), Finland (0.001%), Denmark (0.01%), Norway (0.02%), Canada (0.07%) and United States (0.08%). At 22-23 weeks, neonatal mortality rates were highest in Canada (892.2 per 1000 live births), Denmark (879.3) and Iceland (1000.0), moderately high in the United States (724.1), Finland (794.3) and Norway (739.0) and low in Sweden (561.2). Stillbirth:live birth ratios at 22-23 weeks were significantly lower in the United States (79.2 stillbirths per 100 live births) and Finland (90.8) than in Canada (112.1), Iceland (176.2) and Norway (173.9). Crude neonatal mortality rates were 83% higher in Canada and 96% higher in the United States than Finland. Neonatal mortality rates among live births ≥ 28 weeks were lower in Canada and United States compared with Finland. Post-neonatal mortality rates were higher in Canada and United States than in Nordic countries.CONCLUSIONS: Live birth frequencies and stillbirth and neonatal mortality patterns at the borderline of viability are likely due to differences in birth registration practices, although true differences in maternal, fetal and infant health cannot be ruled out