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

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.