Sample size calculations were performed assuming that 50% of untreated patients will deliver within 7 days of entry. Using an estimate that a 50% increase in this number to 75% would be clinically important, and assuming a Type I error of 0.05 and a Type II error of 0.2, we calculated that a sample size of 58 patients in each group was necessary. The test was one-sided. Assuming a 10% loss to follow-up rate, sixty four patients will be needed in each group.