Congenital Heart Defects and Apgar Score at Birth, a Nationwide Study

Low Apgar scores have been associated with an increased risk of brain injury and neurodevelopmental disorders in newborns with congenital heart defects (CHDs). However, the relation between CHD subtypes and low Apgar scores remains unknown. This study aimed to assess the association between major subtypes of CHD and low (<7) Apgar scores at 5 minutes.

This population-based study included 1 040 474 liveborn singletons in Denmark from 1997 to 2013. The association between CHD and low Apgar scores was estimated by confounder-adjusted, multivariable logistic regression. In mediation analyses, the underlying mechanisms were examined. Low Apgar scores were present in 3.0% of newborns with CHD and in 0.7% of newborns without CHD. Overall, CHD was associated with an increased risk of a low Apgar score (adjusted odds ratio, 2.5 [95% CI, 2.1-3.0]). CHD subtypes associated with the highest risks were anomalous pulmonary venous return (adjusted odds ratio, 5.7 [95% CI, 2.2-14.9]), hypoplastic left heart syndrome (adjusted odds ratio, 5.1 [95% CI, 2.2-11.8]), and transposition of the great arteries (adjusted odds ratio, 3.5 [95% CI, 1.7-7.4]). In mediation analyses, preterm birth explained 25.2% (95% CI, 11.8-38.6) of the association between CHD and low Apgar scores.

Nearly all CHD subtypes were associated with an increased risk of a low Apgar score. The association was most pronounced in severe and potentially cyanotic types of CHD. These findings suggest that CHD is associated with a complicated fetal-to-neonatal transition and highlight the potential for improvements of this process in infants with CHD.