Background: Preeclampsia remains a leading cause of severe maternal morbidity worldwide and its early- and late-onset phenotypes are increasingly recognised as differing in severity and complication profile. This study aimed to compare the pattern of severe maternal morbidity between women with early-onset preeclampsia (EOP) and late-onset preeclampsia (LOP) and to contrast these outcomes with normotensive pregnancies. Methods: A hospital-based case control study was conducted in the Department of Obstetrics and Gynaecology, BIRDEM General Hospital, Dhaka, over six months (March to August 2019). One hundred women with preeclampsia (50 EOP and 50 LOP) and 50 normotensive controls were enrolled consecutively. Structured interview, clinical examination and review of laboratory records were used to document severe maternal complications, including HELLP syndrome, acute kidney injury (AKI) and disseminated intravascular coagulation (DIC). Data were analysed using SPSS, with the chi-square or Fisher exact test applied as appropriate and p<0.05 considered significant. Results: Baseline maternal age, height and weight were comparable between EOP and LOP groups (p>0.05). DIC occurred in 5 (10.0%) women with LOP versus none with EOP (p=0.056) and AKI occurred in 1 (2.0%) LOP case versus none in EOP. No maternal deaths occurred. Compared with controls, HELLP syndrome (10.0% vs 0%, p=0.016) and AKI (8.0% vs 0%, p=0.034) were significantly more frequent among women with EOP, while DIC was significantly more frequent among women with LOP than controls (10.0% vs 0%, p=0.022). Conclusion: Severe maternal morbidity differs qualitatively between early- and late-onset preeclampsia, with EOP more strongly associated with HELLP syndrome and acute kidney injury and LOP more strongly associated with disseminated intravascular coagulation, when each phenotype is compared with normotensive pregnancy.