Objective:To identify and quantitate the risk factors that might be predictive of hemorrhage during abdominal delivery.Methods:Over a 2‐year period, 1610 women underwent cesarean delivery and 127 (7.9%) had hemorrhage, defined as a decrease in hematocrit of 10% or greater, estimated blood loss greater than 1500 mL, or packed red blood cell administration. These women were compared through a casecontrol study design with the next abdominal birth without hemorrhage that could be matched for age, parity, indication for cesarean delivery, type of anesthesia, type of skin incision, and antepartum hematocrit.Results:Preeclampsia (odds ratio 3.6, 95% confidence interval [CI] 1.8‐7.4), disorders of active labor (odds ratio 4.4, 95% CI 1.4‐13.7), Native American ethnicity (odds ratio 6.4, 95% CI 1.8‐22.4), previous postpartum hemorrhage (odds ratio 8.4, 95% CI 1.9‐37.4), and obesity of greater than 250 lb (odds ratio 13.1, 95% CI 1.7‐102.7) were all statistically associated with significant bleeding during abdominal delivery. Combinations of two or more of these factors were associated with a markedly increased risk for hemorrhage, with odds ratios of 18.4 or greater.Conclusions:Patients undergoing cesarean delivery who have factors exposing them to increased risk of hemorrhage can be identified prospectively. These women will benefit greatly from extended preoperative counseling when possible, effective utilization of blood bank technology through type and cross‐match requests, and preventive measures during abdominal delivery to minimize blood loss.(Obstet Gynecol 1994;83:923‐6)