Objectives
This study aimed to estimate the prevalence of children aged 0–19 years who have a parent with a history of heart disease and investigate their sociodemographic characteristics.

Study design
A national register-based study.

Methods
From the Danish Fertility Register and the Danish National Patient Register information on children of parents with ischemic heart disease, arrhythmia, heart failure and heart valve disease in the period 1981–2018 were obtained. Statistical analyses including descriptive statistics, logistic and linear regression were used to illuminate associations between parental heart disease and sociodemographic characteristics.

Results
The study population consisted of 142,480 children aged 0–19 years with at least one parent diagnosed with heart disease, corresponding to every 9th child in Denmark in 2018. The number increased from 4.5% in 2002 to 11.1% in 2018. In the study population most had a father with heart disease (57.8%) and 4.6% had two parents with heart disease. Parents with heart disease had significantly higher odds of being out of work (OR 1.68, 95% CI 1.64; 1.72), in a single-parent household (OR 1.09, 95% CI 1.07; 1.11), divorced or widowed (OR: 1.10, 95% CI 1.08; 1.12), having a lower educational level (OR 1.35, 95% CI 1.33; 1.37), and a lower family income (−42,410 DKR, 95% CI -50,306; −34,514, P < 0.0001) compared to those without heart disease.

Conclusion
Children affected by parental heart disease comprise a substantial part of the Danish population. These have significantly different sociodemographic characteristics than children in families without parental heart disease, which might affect social heritage and parental capacity.