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Risk Score for Maternal Morbidity Can Also Predict Postpartum Hemorrhage

Key findings

  • The Expanded Obstetric Comorbidity Score (EOCS) predicts severe maternal morbidity based on 27 factors: maternal age, prior Cesarean delivery and 25 co-morbidities (medical or related to the current pregnancy)
  • Because postpartum hemorrhage is a principal driver of severe maternal morbidity, researchers at Massachusetts General Hospital wondered whether the EOCS could also predict hemorrhage
  • This retrospective study analyzed data on 45,394 deliveries between 24 and 43 weeks of gestation; the EOCS was calculated for each woman and postpartum hemorrhage was defined as estimated blood loss (EBL) ≥1000 mL regardless of mode of delivery
  • Among women in the top decile of predicted risk (EOCS ≥34), the incidence of postpartum hemorrhage was 12% while in the remainder of the population it was 5% (P<0.001)
  • The EOCS was not as well calibrated for women who reached the second stage, so it may be less useful for stratifying risk at this time point

In September 2020, a paper in Obstetrics & Gynecology introduced the Expanded Obstetric Comorbidity Score (EOCS), a validated tool for predicting severe maternal morbidity. The score is calculated using 27 factors: maternal age, prior Cesarean delivery and 25 co-morbidities (medical or related to the current pregnancy) assigned using ICD-10-CM diagnosis codes.

Massachusetts General Hospital's Mark A. Clapp, MD, MPH, a specialist in the Maternal-Fetal Medicine Program in the Department of Obstetrics and Gynecology, Kaitlyn E. James, PhD, MPH, instructor in Obstetrics, Gynecology and Reproductive Biology, and Anjali J. Kaimal, MD, MAS, maternal-fetal medicine specialist and the director of the Deborah Kelly Center for Clinical Research, asked if this score could also predict postpartum hemorrhage, a principal driver of severe maternal morbidity. They present their results in a research letter published in the American Journal of Obstetrics & Gynecology.

Study Methods

The team retrospectively analyzed data on women admitted for a planned vaginal delivery between 24 and 43 weeks of gestation between July 1, 2016, and July 20, 2020. There were 45,394 deliveries, of which 35,368 had a recorded second stage time.

The EOCS was calculated for each woman. Postpartum hemorrhage was defined as estimated blood loss (EBL) ≥1,000 mL regardless of the mode of delivery. EBL ≥1,500 mL was analyzed in subgroup analysis.

Results

  • Postpartum hemorrhage occurred in 5.7% of deliveries; 1.5% had EBL ≥1,500 mL
  • Among women in the top decile of predicted risk (EOCS ≥34), the incidence of postpartum hemorrhage was 12% while in the remainder of the population it was 5% (P<0.001)
  • The EOCS was less well-calibrated for women who reached the second stage, so it may be less useful for stratifying risk at this time point
  • Among women who had EBL ≥1,500 mL, the EOCS did not identify a high-risk group as clearly as it did for all postpartum hemorrhages

Conclusion

Risk-stratification tools are important to help obstetric clinicians understand and potentially mitigate their patients' risk of delivery-related adverse events. Although designed to predict severe maternal morbidity, the EOCS seems capable of predicting postpartum hemorrhage, which may facilitate the incorporation of this risk tool into clinical practice.

12%
incidence of postpartum hemorrhage among women with EOCS ≥34

5%
incidence of postpartum hemorrhage among women with EOCS <34

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Mark A. Clapp, MD, MPH, Roy H. Perlis, MD, and colleagues demonstrated the potential utility of prenatal ICD-10 codes to identify a group of women who were more than 2 to 3.5 times more likely than others to have severe maternal morbidity.

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Anjali J. Kaimal, MD, MAS, director of the Deborah Kelly Center for Clinical Research in the Department of Obstetrics and Gynecology at the Massachusetts General Hospital, discusses how the center facilitates and supports obstetrics and gynecologic research.