Kidney biopsy during pregnancy: indications, complications, results and therapeutic impact

The diagnosis of kidney disease can be challenging during pregnancy. A kidney biopsy (KB) may be proposed, but there is little recent data available to assess the risk/benefit ratio of this procedure during pregnancy.

In this French nationwide survey, we analysed the indications, complications, histological diagnoses, treatments, and obstetric outcomes of pregnant women who underwent native KB between 2006 and 2025.

We gathered the medical records of 76 patients, with a median age of 29.5 [range 18-42] years, including 2 with twin pregnancies. KB was performed at a median gestational age of 13.5 [range 4-26] weeks. The main indications for KB were: nephrotic syndrome without AKI (40.8%) and non-nephrotic proteinuria without AKI (40.8%). KB led to a diagnosis in 72 (94.7%) patients. The main histological diagnoses were lupus nephritis (43%), focal segmental glomerulosclerosis (13%), membranous nephropathy (13%), IgA nephropathy (12%), and idiopathic nephrotic syndrome consistent with minimal change disease (5%). One patient experienced bleeding requiring transfusion. Specific treatment was initiated in 48 (63.2%) patients after KB: corticosteroids (35.5%), hydroxychloroquine (27.6%), azathioprine (18.4%), calcineurin inhibitor (13.2%), rituximab (2.6%) and belimumab (1.3%). There was a high incidence of preeclampsia (16.4%), small for gestational age (21.3%) and intrauterine fetal death (9.0%) in this cohort. Preterm birth and low birth weight occurred in 65.0% and 56.7% of cases, respectively.

When considered necessary to establish a diagnosis during pregnancy, kidney biopsy performed in the first two trimesters appears to be safe, with a high diagnostic yield and a significant impact on therapeutic decision-making and patient management.