Objective: To estimate the rate of success and risk of maternal morbidities in women with three or more prior caesareans who attempt vaginal birth after caesarean (VBAC).
Design: Retrospective cohort design.
Setting: Multicentre, from 1996 to 2000, including 17 tertiary and community delivery centres in north-eastern USA.
Population: A total of 25 005 women who had had at least one prior caesarean delivery.
Methods: Women who attempted VBAC with three or more prior caesareans were compared with those who attempted after one and two prior caesareans. Univariable and stratified analyses were used to select factors for multivariable analyses for maternal morbidity. Maternal characteristics were compared using a Student's t test, Mann-Whitney U test, chi-square test or Fisher's exact test, as appropriate.
Main outcome measures: The primary outcome was composite maternal morbidity, defined as at least one of the following: uterine rupture, bladder or bowel injury, or uterine artery laceration. Secondary outcomes were VBAC success, blood transfusion and fever.
Results: Of 25 005 women, 860 had three or more prior caesarean deliveries: 89 attempted VBAC and 771 elected for repeat caesarean. Of the 89 who attempted VBAC, there were no cases of composite maternal morbidity. They were also as likely to have a successful VBAC as women with one prior caesarean (79.8% versus 75.5%, adjusted OR 1.4, 95% CI 0.81-2.41, P = 0.22).
Conclusion: Women with three or more prior caesareans who attempt VBAC have similar rates of success and risk for maternal morbidity as those with one prior caesarean, and as those delivered by elective repeat caesarean.