Severe maternal morbidity among delivery and postpartum hospitalizations in the United States.

OBJECTIVES To propose a new standard for monitoring severe maternal morbidity, update previous estimates of severe maternal morbidity during both delivery and postpartum hospitalizations, and estimate trends in these events in the United States between 1998 and 2009. METHODS Delivery and postpartum hospitalizations were identified in the Nationwide Inpatient Sample for the period 1998-2009. International Classification of Diseases, 9 Revision codes indicating severe complications were used to identify hospitalizations with severe maternal morbidity and related in-hospital mortality. Trends were reported using 2-year increments of data. RESULTS Severe morbidity rates for delivery and postpartum hospitalizations for the 2008-2009 period were 129 and 29, respectively, for every 10,000 delivery hospitalizations. Compared with the 1998-1999 period, severe maternal morbidity increased by 75% and 114% for delivery and postpartum hospitalizations, respectively. We found increasing rates of blood transfusion, acute renal failure, shock, acute myocardial infarction, respiratory distress syndrome, aneurysms, and cardiac surgery during delivery hospitalizations. Moreover, during the study period, rates of postpartum hospitalization with 13 of the 25 severe complications examined more than doubled, and the overall mortality during postpartum hospitalizations increased by 66% (P<.05). CONCLUSIONS Severe maternal morbidity currently affects approximately 52,000 women during their delivery hospitalizations and, based on current trends, this burden is expected to increase. Clinical review of identified cases of severe maternal morbidity can provide an opportunity to identify points of intervention for quality improvement in maternal care. LEVEL OF EVIDENCE III.