Attempt and success rates for vaginal birth after Caesarean section in relation to complications of the previous pregnancy

The relationships between prior obstetrical complications and subsequent trial of labour and vaginal birth after Caesarean (VBAC) success likelihood were examined among a cohort of Washington State women with a first livebirth via Caesarean delivery and a second livebirth between 1987 and 1993 (n = 10110). Overall, 64% of the cohort undertook a labour trial, and 62% of those who attempted VBAC delivery were successful, for an overall VBAC rate of 40%. Women with fetal macrosomia, cephalopelvic disproportion, prolonged labour, diabetes, or placental problems in the first pregnancy were less likely to undergo a labour trial in the second pregnancy than those without these factors, while women with prior induced labour, genital herpes, fetal distress, or breech presentation were more likely to attempt vaginal birth. Approximately half of women with prior macrosomia, labour problems, or chronic medical conditions who attempted VBAC succeeded, as did three-quarters of women with prior breech presentation or placental conditions. Overall VBAC rates were around 33% for women with previous fetal macrosomia, labour problems, or chronic medical conditions, and 45-55% among those with herpes, fetal distress or breech presentation at the first birth. Trial of labour should especially be encouraged among women without prior labour problems.