In the vast majority of patients, the cause of congenital heart disease (CHD) is unknown. Some mothers blame themselves for their child’s illness. However, most researchers stress that congenital heart diseases are usually the result of an unknown combination of factors, rather than something related to the birth mother. However, there are some risk factors that have been associated with a higher rate of congenital heart disease. These risk factors include:

Furthermore, the risk of having a child with congenital heart disease increases from eight in 1,000 to 16 in 1,000 if a parent or sibling has congenital heart disease.

Researchers are continuing to search for potential causes of CHD. Recent findings include:

• Infants born to diabetic mothers are five times more likely than others to have heart defects. The researchers noted that all pregnant women with diabetes should have a special ultrasound of the fetal heart performed.
  
  
• Scientists are beginning to identify certain genes that appear linked to CHD. While it is too early to speculate future treatment options that may result from these discoveries, researchers hope the knowledge will lead them to discover additional genes that may play a role in the development of CHD.
  
  
• Exposure to pesticides during pregnancy may increase the risk of a specific type of CHD called transposition of the great arteries (TGA). Researchers found that mothers who reported exposure to herbicides during pregnancy were nearly three times as likely to have a child born with TGA, while women exposed to rat poison were five times as likely to have a child born with TGA. Most of the women noted home and garden exposures to the substances mentions, as opposed to workplace exposure. In addition, the critical exposures occurred during the first three months of pregnancy. However, researchers acknowledged that mothers of infants with CHD might be more likely to remember an exposure incident than mothers of healthy infants and stated that additional research was needed in this area.
  
  
• Patients with oral clefts are 16 times more likely to have a congenital heart defect. The reason for this association is unknown. However, researchers advise that patients with oral clefts should be examined for heart defects before undergoing reparative surgery.