Introduction Neurodevelopmental delay is more common in children born with congenital heart defects (CHD), even with optimal perinatal and peri-operative care. It is hypothesized that fetuses with... Show moreIntroduction Neurodevelopmental delay is more common in children born with congenital heart defects (CHD), even with optimal perinatal and peri-operative care. It is hypothesized that fetuses with CHD are prone to neurological impairment in utero due to their cardiac defect, possibly leading to delayed cortical development. Methods Cerebral cortical maturation was assessed with advanced neurosonographic examinations every 4 weeks in fetuses with CHD and compared to control fetuses. Five different primary fissures and four areas were scored (ranging 0-5) by blinded examiners using a cortical maturation scheme. Results Cortical staging was assessed in 574 ultrasound examinations in 85 CHD fetuses and 61 controls. Small differences in grading were seen in Sylvian and cingulate fissures. (Sylvian fissure: -0.12 grade, 95% CI (-0.23; -0.01) p = 0.05, cingulate fissure: -0.24 grade, 95% CI (-0.38; -0.10) p = <0.001. Other cortical areas showed normal maturation as compared to control fetuses. Conclusion Small differences were seen in three of the nine analyzed cortical areas in CHD fetuses, in contrast to previous reports on progressive third-trimester delay. The clinical implications of the small differences however, remain unknown. Show less