OBJECTIVE: This study aimed to systematically assess the impact of cardiomyopathy on maternal pregnancy outcomes. DATA SOURCES: PubMed, Ovid Embase, Ovid MEDLINE, Cochrane Library, and ClinicalTrials.gov were systematically searched from inception to April 24, 2022. STUDY ELIGIBILITY CRITERIA: Observational cohort, case-control, and case-cohort studies in human populations were included if they reported predefined maternal outcomes for pregnant women with cardiomyopathy (any subtype) and for an appropriate control population (pregnant women with no known heart disease or pregnant women with noncardiomyopathy heart disease). METHODS: Two reviewers independently assessed the articles for eligibility and risk of bias, and conflicts were resolved by a third reviewer. Data were extracted and synthesized according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analyses of Observational Studies in Epidemiology guidelines. RESULTS: A total of 14 studies (n=57,539,306 pregnancies) were eligible for inclusion. Women with cardiomyopathy were more likely to deliver by cesarean delivery than women with no heart disease (odds ratio, 2.96; 95% confidence interval, 2.47-3.55; I2=95%; P≤.00001) or women with noncardiomyopathy heart disease (odds ratio, 1.90; 95% confidence interval, 1.62-2.22; I2=91%; P<.00001). Having cardiomyopathy conferred a greater risk for experiencing severe maternal adverse cardiovascular events during pregnancy when compared with not having any heart disease (odds ratio, 206.64; 95% confidence interval, 192.09-222.28; I2=73%; P<.0001) or having noncardiomyopathy heart disease (odds ratio, 7.09; 95% confidence interval; 6.08-8.27; I2=88%; P<.00001). In-hospital mortality was significantly higher among women with cardiomyopathy than among women with no heart disease (odds ratio, 126.67; 95% confidence interval, 43.01-373.07; I2=87%; P<.00001) or among women with noncardiomyopathy heart disease (odds ratio, 4.30; 95% confidence interval, 3.42-5.40; I2=0%; P<.00001). CONCLUSION: Pregnant women with cardiomyopathy have increased risks for adverse maternal outcomes, including maternal death, when compared with both women with no heart disease and women with noncardiomyopathy heart disease. Our results highlight the importance of preconception risk assessments to allow for informed decision-making before pregnancy. Pregnancies affected by cardiomyopathy are high risk and should be managed by expert, multidisciplinary obstetrical and cardiology teams.