Supplementary Material for: Preeclampsia and onset of renal disorders in the long-term period following pregnancy

Introduction: Preeclampsia is associated with acute renal complications during pregnancy, but the risk of renal sequelae later in life is unclear. We determined if preeclampsia was associated with chronic renal complications in the long-term period following pregnancy.
Methods: We conducted a longitudinal cohort study of 1,431,156 pregnant women in Quebec, Canada with 25,598,024 person-years of follow-up between 1989 and 2023. The main exposure measure was preeclampsia, and outcomes included hospitalization for vascular and nonvascular renal complications up to 34 years after pregnancy. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for the association between preeclampsia and subsequent kidney complications using Cox regression models adjusted for patient characteristics.
Results: Patients with preeclampsia had a higher hospitalization rate for renal complications than patients without preeclampsia (29.4 vs. 19.5 per 10,000 person-years). Preeclampsia was associated with 1.45 times the risk of hospitalization for renal disease during follow-up (95% CI 1.40-1.50). Risks were particularly elevated for renal vascular disease (HR 3.74, 95% CI 3.21-4.37), diabetic kidney disease (HR 3.71, 95% CI 3.18-4.32), and glomerulopathy (HR 3.44, 95% CI 2.92-4.05). Associations were also present with obstructive uropathy (HR 1.44, 95% CI 1.30-1.58). Severe forms of preeclampsia, including early onset preeclampsia (HR 1.90, 95% CI 1.72-2.10) and superimposed preeclampsia (HR 2.52, 95% CI 2.22-2.85) were strongly associated with subsequent renal morbidity.
Conclusion: Preeclampsia, especially severe preeclampsia, is associated with the long-term risk of renal disease. Patients with preeclampsia may benefit from nephrological follow-up in the long-term period after pregnancy.