Trial of labour after caesarean (TOLAC) is associated with increased risk for instrumental delivery.

We compared the rates of instrumental delivery in a cohort of nulliparous women at term (n = 19,416), to primiparous women who attempted labour after prior caesarean (TOLAC) (n = 1747). The rate of instrumental deliveries was higher in the TOLAC group compared to nulliparous gravidas (17.3 vs. 15% respectively, p = 0.001). The difference was more prominent for women who eventually had successful vaginal delivery (TOLAC: 23.9% vs. CONTROLS: 17.1%, p < 0.0001 respectively). Based on our results, previous caesarean whether urgent or elective was associated with an increased risk of instrumental delivery in the subsequent pregnancy.