Material and Method: A retrospective cohort study of term pregnant women in cephalic presentation with labor pain who delivered in Rajavithi Hospital between January 1 and December 31, 2014 was conducted. Those parturients whose membranes were ruptured by amniotomy were study cases and those whose amniotomy were not performed and delivered immediate after the study cases were assigned as the control cases.

Results: Five hundred ninety eight women with uncomplicated pregnancy were enrolled and divided equally into two groups, one of 299 cases with amniotomy and another 299 cases without amniotomy. The present study showed that pregnant women in amniotomy group had a significantly higher rate of cesarean delivery (p<0.001) and birth asphyxia (p = 0.002). The duration of labor, maternal complications, and neonatal complications were not significantly different between the two groups.

Conclusion: Rate of cesarean delivery and birth asphyxia were significantly higher in the amniotomy group compared with the non-amniotomy group.

Keywords: Amniotomy, Duration of labor, Cesarean delivery, Neonatal outcome, Uncomplicated pregnancy