Severe Maternal Morbidity Among Wisconsin Residents at Delivery, 2010-2014

BACKGROUND:  Pregnancy-related deaths are rare in the U.S., but for every pregnancy-related death approximately 100 women experience severe maternal morbidities (SMM) such as eclampsia, sepsis, or hysterectomy. SMM are serious complications of the perinatal period that are caused or exacerbated by pregnancy. National estimates suggest that SMM rates have increased in recent years. Identifying where SMM rates are high can identify opportunities for improving the quality of care and health of mothers.

METHODS:  Hospital discharge data were used to calculate rates of SMM for delivery hospitalizations of Wisconsin residents, including women delivering in Minnesota. ICD-9-CM diagnosis and procedure codes were used to identify delivery hospitalizations with an indicator of SMM using methods described by Kuklina et al. (2008) and Callaghan et al. (2012). The most common indicators of SMM were identified, along with characteristics of the hospitalizations (location, charges) and mothers (race/ethnicity, age).

RESULTS:  The 2010-2014 SMM rate in Wisconsin was 100.4 per 10,000 delivery hospitalizations. This remained stable over the 5-year period (range 95.3-102.9; p for trend =0.75). Of women with at least one SMM, 12.9% had multiple SMMs. The most common types of SMM were blood transfusion (68.8 per 10,000 delivery hospitalizations), operations on the heart and pericardium (8.5), and hysterectomy (7.6). Wisconsin resident women delivering in Minnesota had the highest rate of SMM (124.1), while women delivering in the rural region of the state bordering Minnesota had the lowest regional rate (64.6). Minority mothers had higher rates of SMM (non-Hispanic Black: 148.7, non-Hispanic American Indian: 155.0, non-Hispanic Asian: 137.2, and Hispanic: 126.6) compared to non-Hispanic White mothers (85.8). By age, mothers younger than age 20 (138.5), women ages 35-39 (129.1), and women over age 40 (178.5) had the highest rates  Median charges for delivery hospitalization increased nearly two-fold for each additional SMM experienced.

CONCLUSIONS:  Although SMM rates are currently stable in Wisconsin, some leading conditions differ from those seen nationally (transfusion, disseminated intravascular coagulation, and heart failure). Further, minority mothers and mothers at younger and older ages experience higher rates of SMM. Large differences in the SMM rate between women delivering in Minnesota and in Western Wisconsin may be due to high-risk women from that rural region delivering in risk-appropriate Minnesota hospitals. SMM rates and characteristics will be used to complement maternal mortality review findings and inform the Wisconsin Perinatal Quality Collaborative as they identify quality improvement activities to improve maternal outcomes.