The Epidemiology of Postpartum Hemorrhage in a Large, Nationwide Sample of Deliveries

BACKGROUND: In this study, we sought to (1) define trends in the incidence of postpartum hemorrhage (PPH), and (2) elucidate the contemporary epidemiology of PPH focusing on risk factors and maternal outcomes related to this delivery complication. METHODS: Hospital admissions for delivery were extracted from the Nationwide Inpatient Sample, the largest discharge dataset in the United States. Using International Classification of Diseases, Clinical Modification (ninth revision) codes, deliveries complicated by PPH were identified, as were comorbid conditions that may be risk factors for PPH. Temporal trends in the incidence of PPH from 1995 to 2004 were assessed. Logistic regression was used to identify risk factors for the most common etiology of PPH-uterine atony. RESULTS: In 2004, PPH complicated 2.9% of all deliveries; uterine atony accounted for 79% of the cases of PPH. PPH was associated with 19.1% of all in-hospital deaths after delivery. The overall rate of PPH increased 27.5% from 1995 to 2004, primarily because of an increase in the incidence of uterine atony; the rates of PPH from other causes including retained placenta and coagulopathy remained relatively stable during the study period. Logistic regression modeling identified age <20 or >= 40 years, cesarean delivery, hypertensive diseases of pregnancy, polyhydramnios, chorioamnionitis, multiple gestation, retained placenta, and antepartum hemorrhage as independent risk factors for PPH from uterine atony that resulted in transfusion. Excluding maternal age and cesarean delivery, one or more of these risk factors were present in only 38.8% of these patients. CONCLUSION: PPH is a relatively common complication of delivery and is associated with substantial maternal morbidity and mortality. It is increasing in frequency in the United States. PPH caused by uterine atony resulting in transfusion often occurs in the absence of recognized risk factors. (Anesth Analg 2010;110:1368-73)