The new betacoronavirus, known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the cause of COVID-19, and has spread rapidly around the world, reaching more than 200 countries, around 364 million people and causing more than 5 million deaths according to the World Health Organization, so this paper reports a fatal case of SARS-CoV-2 infection in a young pregnant woman with heart disease, without vertical transmission. A 26 years old patient at 28th week of pregnancy with regular prenatal care, presented dry cough, high fever, and severe respiratory distress. Due to her clinical symptoms, she sought medical care at a cardiology hospital in Northern Brazil. The medical conditions she presented were heart disease, rheumatic fever history and had no recent record of national or international travel. She was hospitalized and after clinical stabilization, she was referred for an emergency cesarean intervention. The young mother and the newborn were transferred to the intensive care unit after surgery, where diagnostic tests for respiratory viral infections, including SARS-CoV-2, were performed. The mother tested positive, while her newborn was negative for SARS-CoV-2 demonstrating no vertical transmission of SARS-CoV-2 in this severe case. This study reveals that despite the mother’s initially mild symptoms, she progressed to severe clinical conditions resulting in death, although no vertical transmission was observed. This report highlights the relevance of comorbidities for the unfavorable clinical course of COVID-19.