///2019 Abstract Details
2019 Abstract Details2019-07-13T07:45:15-05:00

The obstetric comorbidity index for maternal postpartum hemorrhage risk assessment

Abstract Number: F3D-194
Abstract Type: Original Research

Rochelle J. Molitor MD1 ; Brian T. Bateman MD, MSc2; Michaela K. Farber MD3; Julian N. Robinson MD4; Daniela A. Carusi MD, MSc5; Sarah Rae Easter MD6

Background: The obstetric comorbidity index (OB-CMI) is a maternal risk assessment tool that summarizes the burden of maternal comorbidities into a single numerical score (1). The OB-CMI can predict the risk of severe maternal morbidity (SMM) in clinical practice. Postpartum hemorrhage (PPH) is an important source of SMM. The OB-CMI incorporates many risk factors for PPH, but whether the OB-CMI can be used to identify patients at risk for PPH has yet to be evaluated.

Methods: We assembled a prospective cohort of pregnant patients admitted to Labor and Delivery at or beyond 23 weeks’ gestation from February to July 2018. Each patient’s OB-CMI score was calculated on admission and every 12 hours until delivery by the primary nurse. Our primary outcome of interest was PPH requiring transfusion. Secondarily, the presence of hemorrhage-associated SMM was determined by a multidisciplinary panel of clinicians blinded to OB-CMI score using contemporary criteria (2). We analyzed the association between OB-CMI and the aforementioned outcomes using logistic regression and calculated a c-statistic to determine the discrimination of the score.

Results: A total of 2,828 deliveries were included in the study, 53 of which were complicated by PPH requiring transfusion (1.87%). Women requiring transfusion had a higher OB-CMI score than those who did not (median 4, interquartile range (IQR) 2-6 vs. 1, IQR 0-3 p<0.01 respectively). The prevalence of transfusion increased with increasing OB-CMI score (Figure). Women with an OB-CMI of 0-1 had a 0.67% prevalence of transfusion compared to 17.6% for those with a score ≥ 10. The c-statistic for the association between the OB-CMI and transfusion was 0.75 (95% confidence interval (CI) 0.68-0.82) and the c-statistic for hemorrhage-associated SMM was 0.77 (95%CI 0.66-0.87) indicating strong discrimination for both outcomes.

Conclusions: An increasing OB-CMI is associated with an increased risk of transfusion and hemorrhagic morbidity at the time of delivery. The OB-CMI may be useful to prospectively identify high-risk women at risk of PPH to ensure adequate resources are available at delivery.


1. Bateman BT et al. Development of a comorbidity index for use in obstetric patients. Obstet Gynecol. 2013; 122(5):957-65.

2. American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine. Severe maternal morbidity: screening and review. Am J Obstet Gynecol. 2016; 215(3):B17-22.

SOAP 2019