Indications for first caesarean and delivery mode in subsequent trial of labour

A previous caesarean delivery is no longer an indication per se for a subsequent, planned caesarean. We performed this study to identify women suitable for trial of labour after caesarean (TOLAC), investigating the association between the indication for the first caesarean and the risk of unplanned caesarean in the second pregnancy.

We identified women with their first two pregnancies registered in the Swedish Medical Birth Registry 1992-2007. The indications for caesarean in the first pregnancy were determined using a previously published hierarchical system. For each indication group, the rate of caesarean among women with a first caesarean (n = 59 643) and a TOLAC in the second pregnancy was compared with that of primiparae (parity 0) (n = 354 053).

The TOLAC rate was 69.5%. Among women with TOLAC, the uterine rupture rate was 1.1%. The success rate of TOLAC varied substantially based on the indication for the first caesarean (range 51-83%). Multiple births, breech presentation, and placenta praevia in the first pregnancy were associated with marginally increased odds of unplanned caesarean in the second pregnancy when compared with primiparae (adjusted OR 1.27 [95% CI 1.10, 1.48], 1.42 [1.34, 1.51], and 1.65 [1.17, 2.31]; OR, odds ratio; CI, confidence interval). The indications based on complications during labour/delivery, macrosomia, and maternal diabetes, were associated with substantially increased OR: 3.87 [3.70, 4.06], 4.15 [3.74, 4.61], and 4.62 [3.79, 5.63], respectively.

Considering the indications for caesarean in the first pregnancy before recommending a TOLAC or a planned caesarean in the second pregnancy may help to lower the rate of unplanned caesarean deliveries.