OBJECTIVES: Our purpose was to record gestational age—specific data for third-stage duration of labor, frequencies of retained placentas (undelivered at 30 minutes), manual removal of the placenta, and hemorrhage. STUDY DESIGN: Included were 45,852 singleton deliveries ≥20 weeks' gestation from 1984 to 1992. Odds ratios, 95% confidence intervals, and actuarial life analysis with censoring of cases with manual placenta removal were performed. RESULTS: The frequency of retained placentas (2.0% overall) was markedly increased among gestations ≤26 weeks (odds ratio 20.8, 95% confidence interval 17.1 to 25.4) and < 37 weeks (odds ratio 3.0, 95% confidence interval 2.6 to 3.5) compared with term. The frequency of manual removal (3.0% overall) was increased among gestations ≤26 weeks (odds ratio 9.2, 95% confidence interval 7.5 to 11.4) and <37 weeks (odds ratio 2.8, 95% confidence interval 2.4 to 3.1) compared with term. Hemorrhage (3.5% overall) was increased among subjects with manual placenta removal (odds ratio 10.4, 95% confidence interval 9.1 to 11.9); hemorrhage was also increased among gestations ≤26 weeks (odds ratio 3.0, 95% confidence interval 2.3 to 4.0) and <37 weeks (odds ratio 1.2, 95% confidence interval 1.01 to 1.3) compared with term. The frequency of hemorrhage peaked by 40 minutes regardless of gestational age. Life-table analysis predicted 90% of placentas would spontaneously deliver by 180 minutes for gestations at 20 weeks, 21 minutes at 30 weeks, and 14 minutes at 40 weeks; the predicted frequency of retained placentas wa 42% higher than the recorded incidence. CONCLUSIONS: The duration of the third stage decreases and the frequencies of hemorrhage and manual removal decrease with increasing gestational age. Hemorrhage was associated with manual placental removal. Life-table analysis indicated that manual removal of placentas shortened the duration of the third stage of labor, especially among prterm deliveries. A prospective trial is needed to determine whether manual placental removal can reduce hemorrhage among prolonged third stages. © 1995, All rights reserved.