Introduction Sickle cell disease (SCD) in pregnancy is associated with worse maternal and neonatal outcomes. There is limited available data describing burden and outcomes of critically ill obstetric patients affected by SCD in low-income settings. Objectives We aimed to define SCD burden and impact on mortality in critically-ill obstetric patients admitted to an urban referral hospital in Sierra Leone. We hypothesized that SCD burden is high and independently associated with increased mortality. Methods We performed a registry-based cross-sectional study from March 2020 to December 2021 in the high-dependency unit (HDU) of Princess Christian Maternity Hospital PCMH, Freetown. Primary endpoints were the proportion of patients identified in the SCD group and HDU mortality. Secondary endpoints included frequency of maternal direct obstetric complications (MDOCs) and the maternal early obstetric warning score (MEOWS).Results Out of a total of 497 patients, 25 (5.5%) qualified to be included in the SCD group. MEOWS on admission was not different between patients with and without SCD and SCD patients had also less frequently reported MDOCs. Yet, HDU mortality in the SCD group was 36%, compared to 9.5% in the non SCD group (P<0.01), with an independent association with mortality when accounting for severity on admission and occurrence of a MDOC (hazard ratio 2.69; 95%CI 1.21-5.99; P= 0,015). Patients with SCD had a tendency to longer HDU length of stay. Conclusions One out of twenty patients accessing a HDU in Sierra Leone had self-reported SCD. Despite comparable severity on admission, mortality in SCD patients was four times higher than patients without SCD. Optimization of intermediate and intensive care for this group of patients should be prioritized in low-resource settings with high maternal mortality.