Effect of previous vaginal delivery on success of trial of labor in women with one previous lower segment caesarean section: a prospective study

Background: Vaginal birth after caesarean (VBAC) has many advantages but failed trial of labor after caesarean (TOLAC) has increased morbidity and mortality. The objective of this study is to determine the influence of previous vaginal delivery on the success of TOLAC.Methods: A prospective study was conducted on 250 women with history of one previous LSCS who underwent TOLAC. They were divided into two groups: Group 1 which included 184 women with previous LSCS and no vaginal delivery, group 2 included 66 women with previous LSCS and vaginal delivery before or after LSCS. Group 2 was further subdivided into group 2A-34 women with vaginal delivery before LSCS, group 2B-32 women with vaginal delivery after LSCS. The maternal outcome in terms of success rate of VBAC, scar dehiscence and uterine rupture was compared among the study groups. Chi square test was used for statistical analysis.Results: The VBAC success rate of group 1, group 2A and group 2B was 70.7%, 70.6% and 100% respectively. The VBAC success rate of women with history of vaginal delivery after LSCS (Group 2B) was significantly higher than those with no vaginal delivery (Group 1) (p=0.001) and women with vaginal delivery before LSCS (Group 2A) (p=0.003). The VBAC success rate of women with history of vaginal delivery before LSCS was not significantly higher than that of women with previous LSCS and no vaginal delivery (p=0.99).Conclusions: History of prior VBAC is a strong positive prognostic indicator for the success of TOLAC