BACKGROUND: In the context of the COVID-19 pandemic caused by the SARS-CoV-2 virus, viral pneumonia is the leading clinical form of coronavirus infection and a significant cause of maternal mortality. AIM: The aim of this study was to assess the course of severe and extremely severe forms of COVID-19, its impact on pregnancy and fetus, as well as on maternal mortality. MATERIALS AND METHODS: In this retrospective study, we evaluated 39 case histories of patients with severe and extremely severe COVID-19, which were divided into two groups. Group 1 included 22 pregnant women with a severe course of coronavirus infection and a favorable outcome. Group 2 comprised 17 pregnant women in whom complications caused by SARS-CoV-2 were fatal. RESULTS: More than 80% of patients with severe disease course had anaemia in pregnancy. The most significant clinical and anamnestic factors of adverse outcome were gestational diabetes mellitus (p = 0.02), preeclampsia (p = 0.05), and oligoamnios (p = 0.01). Obesity in group 2 was twice more common. The clinical manifestations of the disease in the both study groups were dominated by fever, shortness of breath, weakness and dry cough. In patients with a fatal outcome at the height of the disease, the levels of leukocytosis, urea and lactate dehydrogenase were higher than in those who recovered (p = 0.05). Besides, the levels of alanine transferase and aspartate transaminase were twice as high as in pregnant women who recovered later. Patients in the both study groups required oxygen support as respiratory failure progressed. The vast majority of patients with severe and extremely severe forms of coronavirus infection were in the third trimester of pregnancy. CONCLUSIONS: Women in the third trimester of pregnancy are more susceptible to severe and extremely severe COVID-19 with an unfavorable outcome. Gestational diabetes mellitus, preeclampsia and oligoamnios are significant comorbidities that predispose to severe course and poor outcome in pregnant women and puerperas with COVID-19. The characteristic clinical manifestations of the severe course of coronavirus infection are shortness of breath and fever against a backdrop of significant damage to the lung tissue. A pronounced increase in hepatic enzymes and placental insufficiency is a harbinger of an unfavorable outcome as a manifestation of multiple organ failure.