Additional analyses showed that postpartum hemorrhage in the first pregnancy due to one etiology increased the risk of postpartum hemorrhage in the second pregnancy due to both that etiology and others. "These findings are really quite surprising and are novel," he commented.
For example, women who had hemorrhage due to uterine atony in their first pregnancy had a 3.9-fold higher risk of hemorrhage due to uterine atony in their second pregnancy. But they also had increased risks of postpartum hemorrhage due to retained placenta (3.1-fold), laceration (1.7-fold), and delayed postpartum hemorrhage (1.8-fold).
When the investigators repeated analyses but excluded women with stable risk factors that might be present across the reproductive years, such as fibroids, inherited coagulopathy, and cesarean delivery, the elevated risks of a recurrence of postpartum hemorrhage were essentially unchanged. "This argues that recurrence is mediated by some other factor," maintained Dr. Bateman.
Dr. Bateman disclosed that he had no conflicts of interest related to the research.