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

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. 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. 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. 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. 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.