TOPLINE:

In this multicentre French series of 76 pregnant women who underwent native kidney biopsy at 18 centres, procedures performed during the first two trimesters were associated with a low complication rate and high diagnostic yield; biopsy findings guided specific therapeutic interventions in roughly 63% of patients.

METHODOLOGY:

• Researchers conducted a nationwide retrospective survey to assess the risk-benefit balance of native kidney biopsies performed during early pregnancy.
• They analysed the data of 76 women (median age, 29.5 years) who underwent native kidney biopsy during pregnancy at 18 centres in France between 2006 and 2025, with a median gestational age at biopsy of 13.5 weeks.
• Data collected for all patients included demographic and clinical characteristics, obstetric history, current treatments, renal parameters, indications for kidney biopsy, histologic diagnosis, biopsy-related adverse events, therapeutic interventions, and maternal and foetal complications during pregnancy.
• Indications for kidney biopsy were classified as acute kidney injury (AKI), nephrotic syndrome, non-nephrotic proteinuria, or other conditions.

TAKEAWAY:

• The most common indications for kidney biopsy were nephrotic syndrome without AKI and non-nephrotic proteinuria without AKI, each reported in 40.8% of patients. Other indications included AKI with nephrotic syndrome, AKI with proteinuria, and isolated AKI, affecting 9.2%, 6.6%, and 2.6% of patients, respectively.
• The most frequent histologic diagnosis was lupus nephritis, followed by focal segmental glomerulosclerosis, membranous nephropathy, immunoglobulin A nephropathy, and idiopathic nephrotic syndrome.
• Adverse events related to kidney biopsy occurred in nine (11.8%) patients and included one serious event requiring transfusion. Specific treatment was initiated following biopsy in 63.2% of patients and included corticosteroids, hydroxychloroquine, azathioprine, calcineurin inhibitors, rituximab, and belimumab administered to 35.5%, 27.6%, 18.4%, 13.2%, 2.6%, and 1.3% of patients, respectively.
• Obstetric complications were common; preeclampsia, intrauterine foetal death, and preterm birth occurred in 16.4%, 9.0%, and 65% of patients, respectively, and 21.3% of infants were small for gestational age and 56.7% had low birth weight.

IN PRACTICE:

"This study contributes to a better understanding of the benefit-risk balance of performing KB [kidney biopsy] during pregnancy. The risk appears acceptable in the first two trimesters, with good diagnostic yield and a substantial therapeutic impact, directly guiding clinical management," the authors wrote.

SOURCE:

This study was led by Camille Imbert, AP-HM, CHU Conception, Nephrology Department, Marseille, France. It was published online on May 18, 2026, in Nephrology Dialysis Transplantation.

LIMITATIONS:

The retrospective design, which relied on a call for participation, may have introduced recall bias. The study did not include a control group of women who underwent kidney biopsy postpartum. Additionally, data on renal outcomes after pregnancy, such as remission, progression to end-stage kidney disease, or the need for replacement therapy, were not collected.

DISCLOSURES:

This study did not report any source of funding. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.