Pregnancy in women with nephrotic-range proteinuria: A retrospective cohort study.

Background: Obstetric and kidney outcomes following detection of nephrotic-range proteinuria in early pregnancy have not been well described.

Methods: A retrospective cohort study of chronic kidney disease (CKD) in pregnancy between 2008 and 2018. Outcomes in those with nephrotic-range proteinuria before 20 weeks' gestation were compared to those without nephrotic-range proteinuria.

Results: The study included 37 women with nephrotic-range proteinuria and 62 women without. Pre-pregnancy estimated glomerular filtration rate (eGFR) was similar. Nephrotic-range proteinuria was associated with higher rates of preterm (odds ratio [OR] 1.77, 95% confidence interval [CI]: 1.07-2.92) and early preterm delivery (OR 2.63, 95% CI: 1.12-6.2), and with a requirement for renal replacement therapy at 3 years post-partum (OR 10.72, 95% CI: 2.58-44.47). Tubulointerstitial scarring on kidney biopsy was associated with early preterm delivery and progression to advanced CKD, independent of pre-pregnancy eGFR.

Conclusion: Compared to CKD without nephrotic-range proteinuria, nephrotic-range proteinuria early in pregnancy is associated with higher rates of pre-term delivery and progression to advanced CKD.