The present disclosure defines a method for identifying and/or treating risk and/or occurrence of cardiac defect. As is shown herein, microbiomes are reproducibly and detectably associated with cardiac defect risk factors and changes to the microbiome can directly alter cardiac defect risk. The present disclosure demonstrates that microbial signatures can be used to characterize components of microbiomes that associate with altered risk or occurrence of cardiac defects and to identify treatments to reduce risk or severity of cardiac defects.
