(327) Prolongation of the second stage of labor affects TOLAC success

As shown in Table 1, Mean duration of the 2^nd stage of labor was significantly longer in period II as compared with period I (129.7±48.5 vs. 67.3±35.9 minutes, P< 0.0001). As shown in Table 2, the rate of repeated CS was significantly lower in Period II compared with period I (18.1% vs. 29.7%, P< 0.0001). The incidence of uterine rupture was significantly higher in period II as compared with period I (0.6% vs. 0.4%, p< 0.001), but still within the range reported in the medical literature. The instrumental delivery rate was significantly higher in Period II (26.2% vs. 15.6%, P< 0.0001). The incidence of postpartum hemorrhage and blood transfusion rates were significantly higher in period II compared with period I. The rate of arterial umbilical cord pH < 7 (1.5% vs. 0.7%, P< 0.0001), admission to NICU (2.5% vs. 1.6%, p=o.oo4) and shoulder dystocia (1.8% vs. 1.1%, p=0.007) were significantly higher in period II compared with period I.

Conclusion: Allowing an additional hour for the 2^nd stage of labor is associated with a lower rate of repeated CS but a higher rate of instrumental deliveries, uterine rupture, and fetal acidemia. These findings may warrant further consideration of allowing a prolonged 2^nd stage in patients attempting TOLAC.