Pregnancy in women with immunoglobulin A nephropathy: are obstetrical complications associated with renal prognosis?

Abstract

Background Recent studies regarding immunoglobulin A nephropathy (IgAN) suggest no relationship between pregnancy and disease progression, although complicated pregnancies and impaired renal function are closely related. Methods This study used a propensity-score-matched cohort analysis. Among biopsy-confirmed IgAN women in three hospitals in Korea, those who experienced pregnancy after their diagnosis were included in the study group. Renal outcome was the composite of serum creatinine doubling, estimated glomerular filtration rate (eGFR) halving and events of end-stage renal disease. Pregnancies with preterm birth, low birth weight and pre-eclampsia were defined as complicated. Results Overall, 59 IgAN women who became pregnant after their diagnosis, and the same number of IgAN women who did not experience pregnancy were included in the control group. Although pregnancy itself did not worsen renal outcomes [adjusted hazard ratio (HR): 1.51; 95% confidence interval (CI) 0.57-4.01; P = 0.41], mothers with complicated pregnancies experienced worse renal prognosis, even after adjustment for baseline and pre-gestational characteristics (adjusted HR: 5.07; 95% CI 1.81-14.22; P = 0.002). Moreover, this relationship was only significant in mothers with decreased renal function (eGFR <60 mL/min/1.73 m 2) (adjusted HR: 18.70; 95% CI 1.63-214.40; P = 0.02), baseline hypertension (adjusted HR: 4.17; 95% CI 1.13-15.33; P = 0.03) and overt proteinuria (≥1 g/day) (adjusted HR: 4.21; 95% CI 1.24-14.27; P = 0.02). In contrast, patients who experienced pregnancies without complications showed better renal outcomes than did those without post-biopsy pregnancy (P = 0.01). Conclusion Obstetric complications in patients with high renal risk, rather than pregnancy itself, are associated with renal progression of IgAN women.