In the United States, approximately 120,000 babies are born each year with birth defects. Often, birth defects cannot be explained. Risk factors for birth defects include genetics; lifestyle choices and behaviors; infections during pregnancy, such as cytomegalovirus (CMV), chickenpox (varicella), rubella, or Zika virus infections; and drug, chemical, or ionizing radiation exposures. Many birth defects likely occur as a result of complex interactions of genetics and other risk factors.

Most birth defects occur during the first trimester of pregnancy, while the baby’s organ systems are forming. During critical windows of development, environmental exposures could damage the growth and function of a system or organ.

Scientific studies provide some indication of the links between environmental exposures and several birth defects. Chemicals of potential concern include hazardous waste site contaminants, air pollutants, pesticides, and disinfection by-products in drinking water. However, more research and continued monitoring are needed to better understand the relationship between environmental exposures and birth defects.

The DHSS Environmental Public Health Tracking (EPHT) program obtains data from the Missouri Birth Defects Registry on severe birth defects that epidemiological studies suggest are associated with environmental exposures. These data can be used to investigate spatial and temporal patterns of birth defects in Missouri.

Other risk factors for birth defects include:

  • Smoking, drinking alcohol, or taking certain “street” drugs during pregnancy.
  • Having certain medical conditions such as uncontrolled diabetes before or during pregnancy.
  • Taking certain medicines.
  • Being deficient in folic acid.
  • Having another family member with a birth defect.
  • Being an older mother, typically over the age of 34 years.

Learn more about the birth defects tracked by EPHT.

Available Data


Maps, Charts, Graphs and Tables


Additional Resources