Design: Matched population cohort, three Canadian provinces
Population: 385 pregnancies in 252 living kidney donors vs 1,540 matched non-donor pregnancies
Primary outcome: Hospitalisation with gestational hypertension, pre-eclampsia or eclampsia
Effect: 11.9% vs 8.3%; RR 1.51 (95% CI 1.10–2.08)

This Canadian matched cohort used provincial records from Ontario, British Columbia and Alberta. It compared 385 pregnancies in 252 women who had donated a kidney with 1,540 matched pregnancies in non-donors.

Hospitalisation with gestational hypertension, pre-eclampsia or eclampsia occurred in 11.9% of donor pregnancies against 8.3% (risk ratio 1.51, 95% CI 1.10 to 2.08). Small-for-gestational-age birth was 13.8% against 7.9% (RR 1.86). Most pregnancies after donation were uncomplicated.

Administrative data cannot capture blood pressure or kidney function directly, and matching cannot remove all differences. But the finding is consistent with earlier smaller studies and relevant to anyone counselling a young woman considering donation, or caring for a pregnant donor.

Ask about previous kidney donation at booking; it is easy to miss in a pregnancy history.
Consider closer blood-pressure surveillance in pregnant kidney donors.
Consider fetal growth monitoring, as small-for-gestational-age birth was more common.
Include pregnancy risk when counselling young women considering living donation.

Why it matters

Donors are often young women, and their prenatal care rarely flags the donation.

The statistics, in plain English

A risk ratio of 1.51 means about half as much again, or roughly 4 more cases per 100 pregnancies. The interval excludes 1, but this is observational, so unmeasured differences between donors and non-donors may contribute.