Clinical characteristics and risk factors for maternal deaths due to COVID-19 in Brazil: a nationwide population-based cohort study

Background Monitoring the characteristics and associated factors for death among pregnant and postpartum women with coronavirus disease 19 (COVID-19) is necessary. We investigated the clinical characteristics and risk factors associated with maternal deaths in a nationwide cohort of Brazil. Methods This was a population-based cohort of all pregnant and postpartum women hospitalised with COVID-19 notified to the Sistema de Informacao de Vigilancia Epidemiologica da Gripe of Brazil (SIVEP-Gripe), from February 2020 to September 2021. The primary outcome was time to in-hospital death, with risk factors analysed with univariable and multivariable Cox proportional hazards regression models. Results Cumulative observation time was 248 821 person-days from hospital admission to the end of follow-up for 15 105 individuals. There were 1858 deaths (12.3%) for a maternal mortality rate of 7.5 (95% CI 7.1-7.8) per 1000 patients-days. The cumulative mortality increased over time. Black/Brown ethnicity had a higher risk of death than women self-identifying as White. Women in the North, Northeast, Central-West and Southeast regions had higher risk of death than women in the South region. The characteristics independently associated with death were a postpartum status on admission [adjusted hazard ratio, HR 1.4 (95% confidence interval, CI 1.2-1.6)], pre-existing clinical conditions [adjusted HRs 1.2 (95%CI 1.1-1.3) for one and 1.3 (95%CI 1.1-1.5) for two comorbidities], hypoxaemia on admission [adjusted HR 1.2 (95%CI 1.1-1.4)] and requiring non-invasive [adjusted HR 2.6 (95%CI 2.1-3.3)] or invasive ventilatory support [adjusted HR 7.1 (95%CI 5.6-9.2)]. Conclusion In Brazil, the in-hospital maternal mortality rate due to COVID-19 is high and the risk of death increases with the length of hospitalisation. Socio-demographic and biological factors are associated with an increased risk of maternal death. The presence of respiratory signs and symptoms should be considered early markers of disease severity and an adequate management is necessary. Our findings reinforce the need for vaccination of pregnant and postpartum women against COVID-19.