Purpose: Sub-Saharan Africa has the world’s largest burden of Sickle Cell Disease (SCD), but due to poor care of SCD in childhood most do not reach reproductive ages. Consequently, due to sporadic cases of SCD in pregnancy, there has been little research attention to the problem in this sub region. This is one of the largest study series of SCD deliveries in Sub-Saharan Africa that aimed to establish the incidence and determinants of adverse pregnancy outcomes. Methods: Data of all deliveries from 1999 to 2011 at Muhimbili National Hospital (MNH) in Tanzania were analyzed. Deliveries of SCD were obtained and categorized according to presence or absence of adverse pregnancy outcomes based on set composite criteria. Using IBM SPSS statistics version 19, bivariate and multivariate logistic regression analyses were done to determine factors that were independently associated with adverse pregnancy outcomes. Statistics with p-value < 0.05 were taken as significant. Results: There were 157,473 deliveries during the study period of which 149 were by SCD mothers. The incidence of adverse pregnancy outcomes was 624 per 1000 SCD deliveries. Compared to SCD without adverse outcomes, those with adverse outcomes were more likely to be referred from lower health facilities (37% versus 12.5%, P = 0.001), of lower mean gestation age (36.3 ± 2.3 versus 38.4 ± 1.4, P < 0.001), more prematurity rate (50.7% versus 10.5%, P < 0.001), made lower mean number of antenatal visits (4.7 ± 2.2 versus 6.2 ± 2.4, P < 0.001) and delivered by cesarean section (31.2% versus 19.6%, P < 0.001). After adjusting for confounding factors, the odds of adverse outcomes were independently increased with referred compared to non-referred women (OR = 4.4; 95% CI: 1.2 - 16.8) and among Cesarean section deliveries compared to vaginal deliveries (OR = 4.2; 95% CI: 1.2 - 14.6). The risk of adverse outcomes decreased as the gestation age increased (OR = 0.4; 95% CI: 0.3 - 0.6). Conclusion: The incidence of adverse pregnancy outcomes in SCD is unacceptably high mainly contributed by poor management and prematurity.