Background In sheep, intrauterine anaemia causes increased susceptibility to ischaemic injury in adulthood, but effects on humans are unknown. The aim of this study was to investigate cardiovascular outcome in adults who received intrauterine transfusion for fetal anaemia due to rhesus disease.

Methods Participants were adults who received intrauterine transfusion and their unaffected sibling (s). Assessments included anthropometry, blood pressure, lipids, heart rate variability and cardiac MRI. Analysis was by multiple regression adjusted for age, sex, and birth weight z-score, with data as adjusted means ± SD (95% CI).

Results Compared to unaffected siblings, affected participants had smaller ventricular volumes, for example end diastolic volume indexed to body surface area (EDV/BSA); reduced high density lipoprotein (HDL); increased heart rate variability low frequency/high frequency (LF/HF) ratio indicating augmented sympathetic tone; and lower myocardial blood flow (MBF) at rest and with cold pressor stress, but not during adenosine infusion, indicating impaired endothelial function.

Conclusions Endothelial dysfunction in adults exposed to fetal anaemia may be mediated by augmented sympathetic tone. Taken together with smaller ventricular volumes and reduced HDL, this study provides the first evidence in humans that fetal anaemia may be associated with increased cardiovascular risk in adulthood.