OBJECTIVE: To assess the postnatal persistence of fetal cardiovascular remodelling associated with assisted reproductive technologies (ART) in children at 3 years of age. DESIGN: A cohort study of children conceived by ART. SETTING: Maternal-Fetal Medicine Unit, Hospital Clinic Barcelona, Spain. POPULATION SAMPLE: Eighty singleton pregnancies conceived by ART and 80 spontaneously conceived (controls) followed from fetal life up to childhood. METHODS: Cardiovascular evaluation was performed at 3 years of corrected age, including echocardiography, carotid intima-media (cIMT) by ultrasound, and blood pressure. MAIN OUTCOME MEASURES: Postnatal persistence of cardiovascular changes in children conceived by ART. RESULTS: Compared with controls, children conceived by ART showed larger atria (right atrial area: control 4.9 cm2 (0.9) versus ART 5.5 cm2 (0.9), P < 0.001), more globular ventricles (right ventricular sphericity index: control mean 1.8 (SD 0.5) versus ART 1.6 (0.2), P < 0.001), and signs of systolic (tricuspid annular plane systolic excursion: control 18 mm (2) versus ART 16 mm (3), P < 0.001) and diastolic dysfunction (isovolumic relaxation time: control 68 ms (12) versus ART 79 ms (12), P < 0.001). ART children also presented increased systolic blood pressure (control 90 mmHg (6) versus ART 94 mmHg (5), P < 0.003) and cIMT (control 0.52 μm (0.14) versus ART 0.60 μm (0.16), P < 0.001) as compared with those spontaneously conceived. CONCLUSIONS: Cardiovascular changes previously reported in ART fetuses persist postnatally at 3 years of age. These results underscore the importance of future studies for assessing the long-term cardiovascular health associated with ART. TWEETABLE ABSTRACT: Cardiovascular changes described in fetuses conceived by ART, persist in children at 3 years of age.