To determine the prevalence and timing of autism spectrum disorder diagnosis in a cohort of congenital heart disease (CHD) patients receiving neurodevelopmental follow-up and identify associated risk factors.

Retrospective single-centre observational study of 361 children undergoing surgery for CHD during the first 6 months of life. Data abstracted included age at autism spectrum disorder diagnosis, child and maternal demographics, and medical history.

Autism spectrum disorder was present in 9.1% of children with CHD, with a median age at diagnosis of 34 months and 87.9% male. Prematurity, history of post-operative extracorporeal membrane oxygenation, and seizures were higher among those with autism (p = 0.013, p = 0.023, p = 0.001, respectively). Infants with autism spectrum disorder were older at the time of surgery (54 days vs 13.5 days, p = 0.002), and infants with surgery at ≥ 30 days of age had an increased risk of autism spectrum disorder (OR 2.31; 95% CI =1.12, 4.77, p = 0.023). On multivariate logistic regression analysis, being male (OR 4.85, p = 0.005), surgery ≥ 30 days (OR 2.46, p = 0.025), extracorporeal membrane oxygenation (OR 4.91, p = 0.024), and seizures (OR 4.32, p = 0.003) remained associated with increased odds for autism spectrum disorder. Maternal age, race, ethnicity, and surgical complexity were not associated.

Children with CHD in our cohort had more than three times the risk of autism spectrum disorder and were diagnosed at a much earlier age compared to the general population. Several factors (male, surgery at ≥ 30 days, post-operative extracorporeal membrane oxygenation, and seizures) were associated with increased odds of autism. These findings support the importance of offering neurodevelopmental follow-up after cardiac surgery in infancy.