Membranous Nephropathy in Pregnancy

Primary membranous nephropathy (pMN) is less common in women of child-bearing age. The kidney risk factors to adverse maternal-fetal outcomes and the effects of pregnancy on pMN process need to be investigated.

We retrospectively screened all the patients with biopsy-proven pMN from 2008 to 2018. Any cases of pregnancy that occurred at the time of pMN diagnosis or during follow-up were included in the study. Clinical and pathological data were collected from all patients at the time of kidney biopsy and their gestational results were recorded.

Of the 27 pregnancies with gestational time of 35.9 ± 4.5 weeks, 10 adverse maternal-fetal events occurred, including fetal loss (11%), preterm delivery (26%), and severe preeclampsia (15%). The kidney parameters were relatively stable with all preserved kidney function. Time-averaged urinary protein (p < 0.001) and serum albumin (p < 0.001), maximum urinary protein (p = 0.001) and minimum serum albumin (p = 0.01) before week 20, anti-phospholipase A2 receptor (PLA2R) positivity (p = 0.03), and no remission during pregnancy (p = 0.004) were risk factors to adverse maternal-fetal outcomes. Time-averaged urinary protein and serum albumin correlated with the birth weight percentile of neonates.

Pregnancy in pMN patients showed risks to adverse maternal-fetal events. Heavy proteinuria, especially before week 20 of gestation, severe hypoalbuminemia, positive anti-PLA2R, and no remission were risk factors to worse outcomes.