We used data from the National Birth Defects Prevention Study to identify infants born in North Carolina with available new born blood spots. We processed dried blood spots to characterize DNA methylation patterns and evaluated differences in DNA methylation patterns by birth defect status (no birth defect, diagnosed with Tetralogy of Fallot) and by exposure to air pollution. This dataset is not publicly accessible because: EPA cannot release personally identifiable information regarding living individuals, according to the Privacy Act and the Freedom of Information Act (FOIA). This dataset contains information about human research subjects. Because there is potential to identify individual participants and disclose personal information, either alone or in combination with other datasets, individual level data are not appropriate to post for public access. Restricted access may be granted to authorized persons by contacting the party listed. It can be accessed through the following means: Access to the data can be requested from CDC. Format: The data set is from CDC's National Birth Defect Prevention Study (NBDPS). The data include date of birth and residential address history, as well as other individual-level variables.