The aim of this study was to demonstrate the poor prognosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in unvaccinated pregnant women. In this retrospective study, the clinical and laboratory parameters of 26 pregnant or immediately postpartum patients, who were hospitalised and needed intensive care unit (ICU) follow-up due to coronavirus disease 2019 (COVID-19) infection were reported. All pregnant patients who followed up in the ICU were unvaccinated. The mortality rate was calculated as 34.62% in the patients included in the study who were admitted to the ICU. Among patients hospitalised in the ICU, the maternal mortality and stillbirth rates associated with COVID-19 infection were found to be 156.28/100,000 and 11.54%, respectively. Preterm birth occurred in 58.33% of the patients who delivered. 79.17% of the patients were delivered by caesarean section. Lymphopenia, high ferritin, interleukin-6, lactate dehydrogenase, D-dimer and C-reactive protein values were found to be associated with mortality. The course of pregnant patients with COVID-19 infection is not always predictable. Clinical and laboratory data should be evaluated in combination for disease prognosis. Adequate information should be given about the importance of vaccination.Impact Statement What is already known on this subject? The SARS-CoV-2 infection has caused a public health crisis worldwide. As a result of studies on coronavirus disease 2019 (COVID-19) infected pregnant women, it was observed that there was an increase in maternal and perinatal mortality. There has been an increase in intensive care unit (ICU) admissions, especially after patients infected with the Delta variant. The pandemic continues with an unpredictable course of the new variants. What do the results of this study add? Compared to the pre-pandemic period, COVID-19 infection caused a more than 10-fold increase in maternal mortality, particularly after the Delta variant. In intensive care follow-up, low lymphocyte count, high lactate dehydrogenase, D-dimer, C-reactive protein, ferritin and interleukin-6 values are indicators of poor prognosis. What are the implications of these findings for clinical practice and/or further research? COVID-19 infection causes increased maternal mortality. Considering that all of the patients admitted to the ICU in our study were unvaccinated, pregnant women should be encouraged to get vaccinated.