Is Pregnancy Riskier for Living Kidney Donors? With Amit X. Garg, MD, PhD

A Canadian matched cohort study weighs whether pregnancies after living kidney donation carry added hypertensive risk. About 65% of living kidney donors are female, and roughly 75% are of childbearing age at donation, making the effect of donation on future pregnancies a central question during donor evaluation.¹

Presented at American Society of Nephrology (ASN) Kidney Week 2026 by Amit X. Garg, MD, PhD, and published simultaneously in JAMA, a new matched cohort study offers more precise estimates than earlier, smaller studies. Most donor pregnancies were uncomplicated, though investigators observed a modest increase in hypertensive disorders of pregnancy.¹

Why Evaluate Pregnancy in Living Kidney Donors?

For people with kidney failure, a living donor transplant improves both life expectancy and quality of life, but transplant teams also have a responsibility to understand long-term outcomes for donors. Garg noted that consensus guidance from 2004 was reassuring that donor nephrectomy would not adversely affect future pregnancies. Since then, 3 studies, including a 2015 Ontario analysis from his group, have linked donation to a greater risk of gestational hypertension and preeclampsia.¹,²

“Despite these studies, recent reviews still say there’s uncertainty, and current practice patterns vary. Some people are counseled in certain ways; some people aren’t,” said Garg, professor of medicine, epidemiology and biostatistics at Western University, nephrologist at London Health Sciences Centre, and corresponding author of the study, in an interview with HCPLive.

The new analysis adds British Columbia and Alberta to the earlier Ontario cohort and extends follow-up through 2023. Approximately one-third of donor pregnancies were also included in the 2015 study.¹

How Did the Study Compare Donors and Nondonors?

Using linked provincial administrative health databases, investigators identified living female kidney donors aged 18 to 42 years who donated a kidney between July 1992 and August 2021 and subsequently had singleton pregnancies of at least 20 weeks' gestation, with follow-up through March 2023.¹

Because donors tend to be healthier than the general population, nondonors were assigned a simulated donation date and excluded if they had any of 35 conditions that would preclude donation, including hypertension, diabetes, kidney disease, and lupus.¹ Each donor pregnancy was matched to 4 nondonor pregnancies on delivery date, maternal age at delivery, time from cohort entry to delivery, parity, and income quintile. Province-specific estimates were pooled using meta-analysis.¹

The primary outcome was a composite of hospitalization with a diagnosis of gestational hypertension, preeclampsia, or eclampsia from 20 weeks' gestation through 6 weeks postpartum. Investigators also assessed 12 maternal, fetal, and neonatal secondary outcomes.¹

What Were the Pregnancy Outcomes After Kidney Donation?

The analysis included 385 pregnancies in 252 donors and 1540 matched pregnancies in 1535 nondonors.¹ The primary outcome occurred in 11.9% of donor pregnancies vs 8.3% of nondonor pregnancies (risk ratio [RR], 1.51; 95% CI, 1.10–2.08).¹ The model-based absolute risk difference was 2.7 percentage points (95% CI, −0.8 to 6.1). Investigators presented results descriptively rather than with formal significance testing because of overlap with the earlier cohort.¹ More than 88% of donor pregnancies were unaffected, and fewer than 2% had events recorded before 34 weeks' gestation.¹

Among secondary outcomes, preeclampsia or eclampsia occurred in 7.8% vs 5.5% of pregnancies (RR, 1.52; 95% CI, 1.01–2.29).¹

Small for gestational age (SGA) births occurred in 13.8% of donor pregnancies vs 7.9% of nondonor pregnancies (RR, 1.86; 95% CI, 1.37–2.52). Investigators cautioned that the association could reflect chance given the number of secondary outcomes examined.¹

Rates of severe maternal morbidity, cesarean delivery, postpartum hemorrhage, gestational diabetes, preterm birth or low birth weight, and neonatal intensive care admission were similar between groups, and no stillbirths occurred in either.¹

“So overall, the study shows that people who become pregnant after donation generally have very healthy pregnancies and healthy children. There’s a modest increase in the risk of developing high blood pressure or preeclampsia during those pregnancies,” Garg said.

Investigators noted the administrative data did not include blood pressure, body mass index, or medication use during pregnancy, and outcomes relied on diagnostic codes that could not distinguish disease severity. Donors also received slightly more prenatal surveillance than nondonors, and residual genetic confounding remained possible because many donors were biologically related to their transplant recipients.¹

The findings support counseling prospective donors about pregnancy-related hypertensive risk and informing prenatal care for individuals who become pregnant after donation, according to the investigators.¹

Editor's Note: Garg reported no relevant disclosures.

References

1. Wang C, Naylor KL, McArthur E, et al. Pregnancy outcomes after living kidney donation. JAMA. Published online October 22, 2026. doi:10.1001/jama.2026.21737

2. Garg AX, Nevis IF, McArthur E, et al. Gestational hypertension and preeclampsia in living kidney donors. N Engl J Med. 2015;372(2):124-133. doi:10.1056/NEJMoa1408932