Significant and intricate immune adaptations are essential for the establishment and maintenance of normal pregnancy. Preeclampsia is a morbid, potentially life-threatening disease for both mother and neonate that occurs uniquely in pregnancy, at least in part, due to maternal immune maladaptation. We aim to review the literature that focuses on case reports, diagnostic approaches, and treatment strategies for disorders of the complement alternative pathway (CAP) as related to preeclampsia.There is evidence of complement dysregulation in preeclampsia and HELLP syndrome, similar to that observed in a few rare types of thrombotic microangiopathies. Complement dysregulation may be identified with functional laboratory testing as well as genetic testing. Increased utilization of a standardized diagnostic approach to establish whether persistent and/or severe cases of preeclampsia and HELLP syndrome are complement-mediated may lead to development of future treatment strategies, such as complement-targeted therapy.