The primary antiphospholipid antibody syndrome (PAPS) and systemic lupus erythematosus (SLE) may occur in women of reproductive age, and both syndromes have been reported to exacerbate during periods of hormonal flux such as oral contraceptive administration, pregnancy, or the puerperium. These disorders have features which cause them to resemble other multisystem diseases. PAPS and SLE must be differentiated from preeclampsia with HELLP syndrome and thrombotic thrombocytopenic purpura occurring during pregnancy. These four disorders differ in prognosis and required therapies. We report an instructive case of PAPS in a patient who developed microscopic polyarteritis with significant glomerulonephritis following prostaglandin-induced delivery of a stillborn fetus. We compare the manifestations of PAPS, SLE, HELLP, and thrombocytopenic purpura, and discuss the possible role of hormonal imbalance as a precipitating event.