116 pregnancies undertaken by 70 women with IgA glomerulonephritis and their diagnostic renal biopsies have been reviewed. An IgA diffuse mesangial proliferative lesion with superimposed focal and segmental proliferative lesions (IgA FSP) on diagnostic renal biopsy was associated with a greater incidence of maternal complications than IgA diffuse mesangial proliferative glomerulonephritis with no superimposed lesions (IgA DMP) and IgA diffuse mesangial proliferative glomerulonephritis with superimposed focal and segmental hyalinosis and sclerosis (IgA FSHS) (p less than 0.025). Patients with severe vessel lesions had a significantly greater incidence of fetal loss than those with only mild to moderate lesions (p less than 0.025).