Reduced pre-pregnancy proteinuria is associated with improving postnatal maternal renal outcomes in IgA nephropathy...

In patients with immunoglobulin A (IgA) nephropathy, postnatal renal outcomes vary depending on kidney function and proteinuria. However, whether a decrease in proteinuria prior to conception improves postnatal maternal renal outcomes is unknown.

This was a single-center retrospective study. A total of 52 pregnant women with biopsy-proven IgA nephropathy were enrolled in the study between January 2004 and December 2009. We collected data on proteinuria, which had been measured 1 year prior to conception, at conception, during pregnancy, and postnatally. The study outcomes included changes in estimated glomerular filtration rate (eGFR) and proteinuria.

The median serum creatinine, eGFR, and proteinuria levels at conception were 0.8 (0.5 - 2.6) mg/dl, 91.2 (24.1 - 157.0) ml/min, 0.7 (0.0 - 3.5) g/g, respectively. Compared with values measured at conception, serum creatinine (0.8 - 1.0 mg/dl, p < 0.01) and proteinuria (0.7 - 1.5 g/g, p < 0.01) increased significantly postnatally, while eGFR decreased (91.2 - 77.8 ml/min, p < 0.01). In a multiple linear regression analysis, proteinuria at conception were independently associated with a faster decline in postnatal maternal eGFR (β = 4.50, p < 0.05). In addition, a less decline in maternal eGFR was observed in patients with a reduction in proteinuria (> 30%) prior to pregnancy, compared with those with a less reduction (≤ 30%). As for newborn outcomes, preterm delivery, caesarean section, low birth weight < 2,500 g, and need for neonatal intensive care were 15.4%, 46.2%, 25.0% and 7.7%, respectively.

This study showed that in women with IgA nephropathy, proteinuria was significantly associated with the deterioration of postnatal maternal renal outcomes. Our study also suggests that a strategy for reducing proteinuria prior to pregnancy is required to preserve kidney function after delivery.