Louisiana Environmental Public Health Tracking (LEPHT)

Birth Defects and the Environment

Environmental Factors

Most birth defects are thought to be caused by a complex mix of genetic, behavioral, and environmental factors, although, for many birth defects, exactly how these factors work together is unclear.

While some research exists, much more work is still needed to understand the relationship between the environment and birth defects. Doctors and public health scientists know how some birth defects happen, and in some cases can make recommendations to help prevent them. But the causes of many other birth defects are unclear. Most birth defects likely happen for many reasons, not just one reason. One possible reason is the environment.

Sharing data about when and where birth defects happen will help scientists understand whether these defects might be related to the environment. Gaining this understanding is one of the main reasons why birth defects are part of the Environmental Public Health Tracking Network.

Defining Environment

Currently the tracking program provides air quality and water quality environmental data. However, "environmental" influences on an expectant mother extend beyond the "natural" world we normally think of, such as the outdoor air she breathes, and the water she drinks. There are also her indoor environments such as buildings and homes; the food she eats - that food's nutritional value and whether or not it is pesticide free; and any other number of chemicals, such as medicines, beauty products, or household products she may otherwise come into contact with. All of these would be considered her environment.

These types of environmental factors should be considered separately from an expectant mother's "social environment" for example, which should be physically safe and stress-free, or her access to prenatal and health care.

Exposure and Risk

Environment

It is not clear how many birth defects are related to environmental exposures, such as chemicals, drugs, and ionizing radiation. 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. We need more data, though, to make these connections clearer.

Living near a hazardous waste site has been identified as a possible risk factor for birth defects, such as neural tube defects, which are defects in the development of the brain and spinal cord, and 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.

Mother's Age

Women over the age of 35 years have an increasing chance of having a child with Down syndrome than women who are younger. Teenage mothers are more likely to have a baby born with gastrochisis—a defect in the abdominal wall.

Genetics

Some birth defects are caused by genetic problems. Sometimes, these birth defects run in families, but other times they will occur even when there is no one else in the family who has this problem. Communities or populations from a shared heritage may see higher incidences of a specific genetic problem. The root causes of genetic problems are difficult to pinpoint, but even these may have relationships to past environments or a combination of other factors. Preliminary research has shown there may be a potentially higher than normal frequency of certain rare genetic disorders among the Acadian people. To learn more about your risk of having a baby with a genetic abnormality, you can talk with a clinical geneticist or genetic counselor.

Behavior
If a woman takes certain drugs during her pregnancy, the chance of birth defects in her offspring is increased. Also, women who smoke and use alcohol while pregnant have a higher risk of having a baby with certain birth defects. Read about Fetal Alcohol Spectrum Disorders (FASD) »