Pregnancies complicated by PE showed higher rates of prenatal care at other centers, disease flare-ups, LN, HTN, associated APS, a history of PE, proteinuria, positive anti-dsDNA antibodies, at least one positive aPL, and lower serum C3 and C4 levels than those without PE (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.019, p < 0.001, p = 0.033, p = 0.02, p = 0.018, and p < 0.001, respectively). This evidence concerns the gene C4A and hypertensive disorder.