Changes in the diagnosis of congenital cardiovascular malformations during the 1st year of life: impacts on epidemiological risk factor associations.

Many epidemiological studies base their classification of congenital cardiovascular malformations in newborns upon a single, initial diagnosis. This study aimed to evaluate the effect of subsequent diagnostic investigations on the results of epidemiological studies. We used diagnostic codes from the Baltimore-Washington Infant Study from the time of birth and at ~1 year of age.