Comparison of severe maternal morbidity in pregnancy by modified World Health Organization Classification of maternal cardiovascular risk.

BACKGROUND: To compare rates of severe maternal morbidity (SMM) for pregnant patients with a cardiac diagnosis classified by the modified World Health Organization (mWHO) classification to those without a cardiac diagnosis. METHODS: This retrospective study using the 2015-2019 Nationwide Readmissions Database identified hospitalizations, comorbidities, and outcomes using diagnosis and procedure codes. The primary exposure was cardiac diagnosis, classified into low-risk (mWHO class I and II) and moderate-to-high-risk (mWHO class II/III, III, or IV). The primary outcome was SMM or death during the delivery hospitalization; secondary outcomes included cardiac-specific SMM during delivery hospitalizations and readmissions after the delivery hospitalization. RESULTS: A weighted national estimate of 14,995,122 delivery admissions was identified, including 46,541 (0.31%) with mWHO I-II diagnoses and 37,330 (0.25%) with mWHO II/III-IV diagnoses. Patients with mWHO II/III-IV diagnoses experienced SMM at the highest rates (22.8% vs 1.6% for no diagnosis; with adjusted relative risk (aRR) of 5.67 [95% CI: 5.36-6.00]). The risk of death was also highest for patients with mWHO II/III-IV diagnoses (0.3% vs <0.1% for no diagnosis; aRR 18.07 [95% CI: 12.25-26.66]). Elevated risk of SMM and death persisted to 11 months postpartum for those patients with mWHO II/III-IV diagnoses. CONCLUSIONS: In this nationwide database, SMM is highest among individuals with moderate-to-severe cardiac disease based on mWHO classification. This risk persists in the year postpartum. These results can be used to enhance pregnancy counseling.

Duke Scholars

Author Jerome Jeffrey Federspiel Obstetrics and Gynecology, Maternal Fetal Medicine