Tracking Network: Birth Defects and the Environment

CDC's Tracking Network: Understanding the Connections between Birth Defects and the Environment

Every 4 and half minutes, a baby is born with a birth defect in the United States. That equals more than 120,000 babies born each year with a birth defect. Yet the causes of most birth defects are unknown.

Birth defects are thought to be the result of a complex combination of factors, including genes, prenatal behaviors, and the environment. Expectant parents are often unaware of the relationship between these factors and can unknowingly put their unborn child at risk.

CDC's Tracking Network

The Centers for Disease Control and Prevention (CDC) has created a tool that will help us better understand how birth defects may be impacted by the environment. Once we know more about these connections, we can do more to help prevent birth defects. The National Environmental Public Health Tracking Network (Tracking Network) is a tool that stores data about when and where certain health events, such as birth defects, occur. This information can help us to understand the relationship between birth defects, environmental factors, and our actions. It does this by taking data that would traditionally be kept separate by many government and public health agencies, sharing it, and offering organizations a more complete look at the problem.

Environmental Exposures and Birth Defects

Radon test results by county in Washington State
It is not clear how many birth defects are related to environmental exposures, such as pesticides and pollutants in our air and water. Some endocrine-disrupting chemicals, including polychlorinated biphenyls (PCBs), dioxins, and pesticides, have been linked to nervous system defects and developmental problems such as reduced muscle tone and response. But, we need more data to make these connections clearer.

Living near a hazardous waste site has been identified as a possible risk factor for birth defects including: spina bifida, cleft lip or palate, gastroschisis, hypospadias, chromosomal congenital anomalies such as Down syndrome, and some heart and blood vessel defects.

Exposure to disinfection by-products in drinking water such as trihalomethanes, or THM, may increase the risk of some types of birth defects which affect the brain and spinal cord, the urinary tract, and the heart.


As risk factors are better understood, the scientific and medical communities will not only better understand the cause of many birth defects, but they will help you be better prepared to avoid them. The Tracking Network website provides tips that can be used by expectant parents to help them have the healthiest pregnancy possible.

Florida's Tracking Program: Educating Pregnant Women about Safe Fish Consumption

Florida is one state that is using the Tracking Network to address an environmental hazard, mercury, which poses a risk to having a healthy pregnancy. Mercury is a toxin that occurs in the environment naturally and as a result of industrial pollution. It can damage the nervous system of young children and developing fetuses. Methylmercury is a form of mercury found in some fish and shellfish and poses a risk to people who consume contaminated seafood. In Florida, researchers evaluated fish eating patterns and mercury levels in hair samples from women of child-bearing age. Results showed that women of childbearing age in two Florida counties consumed more fish than their counterparts in other areas of the United States and that their hair-mercury levels were higher than the participants of the study who did not consume fish.

Because of these study results, the Florida Tracking Program created the Fish for Your Wallet Card. It contains information about what types and amounts of fish to eat. It encourages women to enjoy the health benefits of certain kinds of fish, but also avoid unsafe amounts of mercury. Check out Florida's Tracking in Action video to learn more about the Florida Tracking Program's safe fish consumption project.

You can also learn more about this important topic and other health conditions affected by the environment at

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Page last reviewed: January 13, 2014