Relationship of birth weight with congenital cardiovascular malformations in a population-based study.

INTRODUCTION: A known comorbidity of congenital cardiovascular malformations is low birth weight, but the reasons for this association remain obscure. This retrospective study examines the relationship between congenital cardiovascular malformations and the birth weight of singletons, taking into account differences in gestational age and other factors. METHODS: Using data from the retrospective, population-based Baltimore-Washington Infant Study, six types of congenital cardiovascular malformations were investigated in comparison with controls (n=3519) through linear regression: d-transposition of the great arteries (n=187), other conotruncal heart defects (n=361), endocardial cushion defects (n=281), left heart obstructive lesions (n=507), atrial septal defects (n=281), and membranous ventricular septal defects (n=622). RESULTS: Infants with conotruncal heart defects (-218 g), endocardial cushion defects with Down syndrome (-265 g), endocardial cushion defects without Down syndrome (-194 g), left heart obstructive lesions (-143 g), atrial septal defects (-150 g), and membranous ventricular septal defects (-127 g) showed significant birth weight deficits, adjusting for gestational age, and other covariates. Infants with d-transposition of the great arteries (-67 g) did not show significant birth weight deficits compared with the control group. DISCUSSION: The degree of birth weight decrement appears to be highly related to the specific type of congenital cardiovascular malformation. As a whole, these infants do not exhibit low birth weights solely because of being premature, and thus other mechanisms must underlie these associations.