Postpartum progression of chronic kidney disease in patients with chronic glomerulonephritis

Background: In the recent years, pregnancy outcomes in women with primary chronic glomerulonephritis (CGN) have been encouraging despite increased incidence of complications and preterm birth. However, the impact of pregnancy on CKD progression in glomerulonephritis remains understudied. Aim: To evaluate the effect of pregnancy on CKD progression in the postpartum period in patients with primary CGN. Materials and methods: This was an observational longitudinal study. The study group included 40 patients with CGN and CKD G1G3b, who had 40 deliveries from January 2009 to November 2022. The control group included 35 patients with CGN who had no pregnancies after CKD was diagnosed. Serum creatinine and estimated glomerular filtration rate (GFR) were assessed during the follow up, recording the development of CKD G5. Results: The annual rate of GFR decline in the study group was -4.6 [-8.0; -2.5] ml/min/1.73 m2, and in the control group -1.8 [-5.8; +1.5] ml/min/1.73 m2 (p = 0.056). After complicated pregnancy (preeclampsia, placental insufficiency, increase in proteinuria, worsening of arterial hypertension, acute kidney injury), the annual rate of GFR decline was -6.4 [-13.4; -3.5] ml/min/1.73 m2, which was higher than in the controls (p = 0.042). There were no significant differences in survival without GFR decrease by 30%, 50% and without CKD G5 between the study and the control groups. However, CKD G5-free survival in the patients with complicated pregnancy was lower than that in the controls (p = 0.022) and in those with uncomplicated pregnancies (p = 0.009). Eleven (11) of 40 patients in the main group and 3/35 in the control group reached CKD G5. The time from delivery to CKD G5 was 4.83 [2.08; 7.07] years. Among women who reached end-stage renal failure after childbirth, there were significantly more patients with CKD G3, proteinuria 1 g/day during pregnancy, arterial hypertension at baseline and during pregnancy, preeclampsia, acute kidney injury, delivery at less than 37 weeks of gestation, with neonates requiring treatment at intensive care unit, and unfavorable pregnancy outcomes. Conclusion: Renal survival in the women with primary CGN who had been pregnant was not significantly different from that in the women who did not have pregnancies; however, complicated pregnancy increased the rate of kidney function decline.