Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal nonneoplastic hematopoietic stem cell disease characterized by an acquired mutation of the PIG-A gene with reduction or absence of CD55 and CD59. The absence of these proteins renders PNH erythrocytes susceptible to complement-mediated hemolysis. We report the case of a PNH patient before and during pregnancy until delivery. We observed and treated some postpartum thrombotic complications. Eculizumab should be used with caution in pregnancy. There are several reports supporting its use in these patients. This case should be considered paradigmatic of a series of clinical situations that may occur in the course of a pregnancy in patients with PNH: increased need for transfusion, need to increase the dose of Eculizumab, and insurgence of fetal sufferance. Moreover, after delivery, the patient, despite adequate prophylaxis with low-molecular-weight heparins, presented severe complications: development of pleural and peritoneal effusion, pulmonary embolism, bilateral upper limbs thrombophlebitis, and a possible abdominal angina with a transient paralytic ileus. All these complications were overcome and now the baby is healthy and the mother has returned to the usual therapeutic regimen.