Certain conditions and illnesses observed in expectant mothers can increase the risk of congenital heart anomalies in their babies. The primary factors that elevate this risk include:

* Exposures: The mother's exposure to teratogenic agents (medications, chemicals), specific infections (especially rubella, cytomegalovirus, etc., during the first trimester of pregnancy), or high-dose ionizing radiation. Excessive alcohol consumption is also a risk factor.
* Existing Medical Conditions:
* Uncontrolled Diabetes: Ineffective management of diabetes in its early stages can increase the risk of congenital heart disease from 0.6-0.8% to 4-6%.
* Phenylketonuria (PKU): This risk can rise to 14% for babies of mothers with phenylketonuria.
* Connective Tissue Diseases: The mother having connective tissue diseases.
* Family History: A family history of congenital heart disease, particularly on the maternal side.