Risk Factors for Pregnancy Outcomes in Patients With IgA Nephropathy: A Matched Cohort Study

Background: The outcomes of pregnancy in immunoglobulin A nephropathy (IgAN) are uncertain. This study assessed the effects of pregnancy on kidney disease progression and risk factors for adverse pregnancy outcomes in IgAN. Study Design: A matched-cohort study. Setting & Participants: Women with IgAN with at least one pregnancy, 1 year of follow-up, and kidney function and proteinuria measurement at baseline (time of biopsy) matched with nonpregnant women with IgAN from Peking University First Hospital. Predictors: Pregnancy, treated as a time-dependent variable; proteinuria; hypertension; and estimated glomerular filtration rate (eGFR). Outcomes: Kidney disease progression, defined as eGFR halving or end-stage kidney disease; rate of eGFR decline; and adverse pregnancy outcomes, including severe pre-eclampsia, intrauterine death, embryo damage, fetal malformation, and induced and spontaneous abortions. Results: Of 239 female patients, 62 women had 69 pregnancies and 62 matched nonpregnant patients were selected as controls. Pregnant patients had median proteinuria at baseline with protein excretion of 1.27 (range, 0.06-7.25) g/d and mean eGFR of 102.3 (range, 40.0-139.0) mL/min/1.73m(2). During a mean follow-up of 45.7 months, 4 patients in the pregnancy group and 6 in the nonpregnancy group had kidney disease progression events. Time-dependent Cox analysis showed that pregnancy was not an independent risk factor for kidney disease progression events (HR, 1.2; 95% CI, 0.3-5.7). There was no significant difference in the median rate of eGFR decline in the 2 groups (-2.5 vs -2.4 mL/min/1.73m(2) per year; P = 0.7). Adverse pregnancy outcomes were observed in 15 patients. Proteinuria during pregnancy (OR, 1.39; 95% CI, 0.96-2.01) was a borderline predictor of adverse pregnancy outcomes. Limitations: Retrospective study, most patients had preserved kidney function, study underpowered to detect a difference in kidney failure events. Conclusions: The study does not permit a definitive conclusion about the effect of pregnancy on kidney disease progression in IgAN. (C) 2014 by the National Kidney Foundation, Inc.