Membranous Nephropathy in Pregnancy

Background: 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. Methods: 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. Results: 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. Conclusions: 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.