RESUMO
OBJECTIVE: To identify risk factors at caesarean section (CS), related to failure of a trial of labour (TOL) in subsequent pregnancy. STUDY DESIGN: Hospital records (1988-1999) of the index pregnancy were reviewed at caesarean delivery for oxytocine use, indication for caesarean, dilatation of cervix, speed of dilatation, duration of contractions and birth weight. The records of the subsequent pregnancy were reviewed for successful vaginal birth after caesarean (VBAC), maternal and neonatal outcome. Data were tested for statistical significance with a Mantel-Haenszel equation for odds ratios (OR, with 95% confidence interval (CI)), a Fisher exact test or a Student's 't'-test. RESULTS: From 214 women with a previous caesarean section, 68.7% underwent a TOL, which was successful in 71.4%. A labour pattern during the index pregnancy characterised by oxytocine use (OR=3.1; 95% CI=1.4-7.1), contractions for more than 12h (OR=3.0; 95% CI=1.3-7.0) and cervical dilatation less than 1cm/h (OR=5.6; 95% CI=1.1-39.4) increased the risk of a failed TOL at subsequent labour significantly. CONCLUSION: Women who attempt VBAC may be informed that a labour pattern of their index pregnancy characterised by oxytocine use, contractions for more than 12h and slow dilatation is associated with a reduced chance of success. A partograph obtained during first labour can be a managerial tool for subsequent labour.