INS A population-based case-control study 4 estimated the relation of single-layer closure at previous caesarean delivery, and other pre-labour and intra-partum risk factors for complete uterine rupture in trial of vaginal birth after a caesarean (TOL) at term. All women (n = 39 742) recorded in the Danish Medical Birth Registry (DMBR) during a 12-year period (1997-2008) with a singleton pregnancy at term and TOL were analyzed. Women with a complete uterine rupture were identified as cases (n=175). Controls were selected in the DMBR as the following two births with TOL at term and no uterine rupture (n=272). After adjustment for possible confounding factors there was no association between single layer closure and uterine rupture (aOR 1.38, CI 0.88 to 2.17). Significant risk factors were: Induction with an unfavourable cervix (aOR 2.10 CI 1.19 to 3.71), epidural (aOR 2.17 CI 1.31 to 3.57), augmentation by oxytocin for more than one hour (aOR 2.03 CI 1.20 to 3.44), and birth weight≥ 4000g (aOR 2.65 CI 1.05 to 6.64). Previous vaginal delivery (aOR 0.41 CI 0.25 to 0.68) and inter-delivery interval of more than 24 months (aOR 0.38 CI 0.18 to 0.78) reduced the risk of uterine rupture.
A Danish prospective cohort study 3 compared outcomes with trial of labor after one cesarean (TOL, n=1161) or elective repeat cesarean delivery on maternal request (ERCD-MR, n=622). TOL was associated with an increased risk of neonatal depression (OR 3.6, 95% CI 1.1 to 19.1) and neonatal intensive care unit admission (adjusted OR 1.9, 95% CI 1.3-2.8). Within the TOL group 67% delivered vaginally. In the TOL group 1.3% (n = 15) of the women had a complete uterine rupture. None of these infants had sequelae after 12 months. Significant risk factors for emergency cesarean were no prior vaginal delivery (adjusted OR 1.8, 95% CI 1.1-3.0), index emergency cesarean during labor (adjusted OR 3.0, 95% CI 2.3-4.1), maternal age≥35 years (adjusted OR 1.9, 95% CI 1.3-2.8), pre-pregnancy body mass index≥30 (adjusted OR 2.1, 95% CI 1.3-3.3), and birthweight 4000-4499 g (adjusted OR 1.5, 95% CI 1.1-2.1). Uterine rupture was associated with the use of epidural analgesia (OR 2.2, 95% CI 1.1-4.9) and no prior vaginal delivery (p = 0.03).
A systematic review 1 including 292 articles was abstracted in DARE. The differences in the rate per 10 000 patients between trial of labour (TOL) and elective repeat caesarean section (ERCS) were as follows (negative result means a lower rate in the TOL group): maternal death -1.69, uterine rupture 23.9, hysterectomy -3.26, bleeding -58.6, infection or fever -5.22, bladder injury 15.4, overall infant death 9.87, 5-minute Apgar score<7 85.0. According to the authors, a woman should be given information on both delivery methods and encouraged to undergo TOL (trial of labour), but her preference for ERCS should be respected.
Another systematic review 2 abstracted in DARE included 17 studies with a total of 4 500 women. Probability of vaginal delivery for woman undergoing trial of labour ranged from 49% to 84%. Maternal mortality for trial of labour was 1.9 per 1 000. Perinatal mortality was 58 per 1 000. The authors conclude that a policy of trial of labour has a success rate comparable to that observed in developed countries.
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