The third stage of labor: a study of outcomes in the second trimester of pregnancy.

Objective: To evaluate the length of the third stage of labor in second trimester pregnancies, to determine the rate of complications such as hemorrhage or infection, and to determine the ideal timing for delivery of the placenta in these pregnancies.

Study Design: A review of 121 consecutive vaginal deliveries between 16 and 27 gestational weeks was performed. Length of the third stage of labor was determined, as well as the composite endpoint of need for manual or instrumented removal of the placenta, or development of chorioamnionitis or endometritis.

Results: Women who delivered at < 23 weeks' gestational age had a significantly longer length of the third stage of labor than did women who delivered at > or = 23 weeks' gestational age (47 minutes vs. 11 minutes, p < 0.01) and were more likely to have chorioamnionitis (30.6% vs. 12.5%, p < 0.05). A third stage of labor > 30 minutes was associated with an increase in manual or instrumented delivery of the placenta (49.0% vs. 14.9%, p < 0.002), a greater decrease in hemoglobin (-1.6 g/dL vs. -0.8% g/dL, p < 0.01), and a higher rate of chorioamnionitis (35.8% vs. 13.6%, p < 0.01). Receiver operating characteristic curve analysis showed optimal timing for delivery of the placenta is < 60 minutes.

Conclusion: Midtrimester deliveries are at increased risk of retained placenta and chorioamnionitis. The optimal timing for placenta delivery is < 60 minutes.