Severe Maternal Morbidity According to Mode of Delivery Among Pregnant Patients With Cardiomyopathies.

BACKGROUND: Women with cardiomyopathies are at risk for pregnancy complications. The optimal mode of delivery in these patients is guided by expert opinion and limited small studies. OBJECTIVES: The objective of this study is to examine the association of delivery mode with severe maternal morbidity events during delivery hospitalization and readmissions among patients with cardiomyopathies. METHODS: The Premier inpatient administrative database was used to conduct a retrospective cohort study of pregnant patients with a diagnosis of a cardiomyopathy. Utilizing a target trial emulation strategy, the primary analysis compared outcomes among patients exposed to intended vaginal delivery vs intended cesarean delivery (intention to treat). A secondary analysis compared outcomes among patients who delivered vaginally vs by cesarean (as-treated). Outcomes examined were nontransfusion severe maternal morbidity during the delivery hospitalization, blood transfusion, and readmission. RESULTS: The cohort consisted of 2,921 deliveries. In the primary analysis (intention to treat), there was no difference in nontransfusion morbidity (adjusted OR [aOR]: 1.17; 95% CI: 0.91-1.51), blood transfusion (aOR: 1.27; 95% CI: 0.81-1.98), or readmission (aOR: 1.03; 95% CI: 0.73-1.44) between intended vaginal delivery and intended cesarean delivery. In the as-treated analysis, cesarean delivery was associated with a 2-fold higher risk of nontransfusion morbidity (aOR: 2.44; 95% CI: 1.85-3.22) and blood transfusion (aOR: 2.26; 95% CI: 1.34-3.81) when compared with vaginal delivery. CONCLUSIONS: In patients with cardiomyopathies, a trial of labor does not confer a higher risk of maternal morbidity, blood transfusion, or readmission compared with planned cesarean delivery.