Trial of labor after caesarean section in low risk pregnancies: is it risky?

ABSTRACT

PURPOSE: To evaluate the influence of a previous caesarean section on adverse composite maternal and perinatal outcome in women who attempted a trial of labor. METHODS: This historical cohort study analyzed maternal and perinatal outcome in women with otherwise low risk pregnancies at term who underwent a trial of labor after a caesarean section (TOLAC). The primary outcome measure was the adverse composite outcome. Secondary outcome measures were amongst others the caesarean section rate and the mode of vaginal delivery. RESULTS: The adverse composite outcome was more frequently in the previous caesarean section group compared to women with no previous caesarean Sect. (22.3% vs. 15.6%, p < 0.0001). The percentage of caesarean Sect. (15.4% vs. 8.2%, p < 0,0001), uterine rupture (1.0% vs. 0.02%, p < 0.0001), placental abruption (1.1% vs. 0.3%, p = 0.0014), vaginal operative delivery (16.0% vs. 8.6%, p < 0.0001), pH < 7.10 (3.7% vs. 2.5%, p = 0.0151), base excess < -12 (3.2% vs. 2.2%, p = 0.0297), abnormal cardiotocography (22.5% vs. 13.9%, p < 0,0001) and fetal blood analysis (6.2% vs. 2.6%, p < 0.0001) was significantly higher in women with a previous caesarean section. Taking the parity into account, these differences could only been seen in women without a previous vaginal delivery. In parous women with a previous vaginal delivery and a caesarean section in history, the adverse composite did not differ between the groups. Only the rate of pH < 7.1 was higher in women after a caesarean Sect. (4.5% vs. 1.8%, p = 0.0436). CONCLUSION: Trial of labor after caesarean in otherwise low risk pregnancies is associated with a higher rate of complications especially if there is no history of vaginal delivery.