We herein report a case of spontaneous pregnancy and preterm delivery in a 29-year-old patient with myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis. Her basal serum creatinine level before pregnancy was 1.4 mg/dL and her urinary protein level was approximately 2 g/day. The proteinuria and hematuria increased during pregnancy, and the patient was admitted to our hospital and treated with prednisolone (PSL). At 27 weeks of gestation, she delivered a live infant weighing 848 g via cesarean section. No relapse of ANCA-associated glomerulonephritis occurred.