Pregnant women with renal disease are at high risk of perinatal complications and renal impairment. Here, we report the outcomes of 4 pregnancies complicated by renal disease diagnosed during pregnancy and the puerperal period. Case 1: Urine test had been positive for protein from 8 weeks of pregnancy, and chronic kidney disease stage G4 was diagnosed at 25 weeks of pregnancy. Renal impairment worsened over time, and cesarean section was performed due to non-reassuring fetal status at 32 weeks of pregnancy. Case 2: Urine test had been positive for protein since before pregnancy, and chronic glomerulonephritis was diagnosed at 15 weeks of pregnancy. Gradual impairment of renal function started at 31 weeks of pregnancy, and the patient had a vaginal delivery at 37 weeks of pregnancy. Case 3: Urine test had been positive for protein since before pregnancy, and hypertension and urine protein were observed since around 26 weeks of pregnancy. Cesarean section was performed due to acute renal failure at 36 weeks of pregnancy. Chronic glomerulonephritis was suspected after childbirth. Case 4: Blood pressure became uncontrollable beginning around 28 weeks of pregnancy, and cesarean section was performed due to sudden worsening of hepatic and renal functions at 31 weeks of pregnancy. Autosomal dominant polycystic kidney disease was diagnosed after childbirth. Pregnancies complicated by renal disease need to be managed carefully with monitoring of blood pressure and renal function. Cooperation with a renal specialist is crucial throughout the perinatal and puerperal periods.