Birth Defects Data

A birth defect is a problem that happens while the baby is developing in the mother's body.  Most birth defects happen during the first three months of pregnancy. A birth defect may affect how a baby's body looks, works, or both.

Access the birth defects data

There are a few different data sources for understanding how often birth defects happen. The Wisconsin Birth Defects Registry began collecting data on birth defects in 2004. However, that registry has been an opt-in system, meaning birth defect reporters (such as physicians) had to get parental consent to report a birth defect. As a result, the registry only caught some of the birth defects in Wisconsin during this time.

In September 2017, budget legislation changed the Wisconsin Birth Defects Registry from an opt-in system to an opt-out system. This means that birth defect reporters will report defects to the registry, unless parents ask them not to do so. Beginning in 2018, collection of data via the opt-out registry is expected to improve birth defects surveillance, which should lead to better data in the future.

While we are waiting for those improved data, we are hosting data from birth certificates and hospitalization discharges to estimate the number and types of birth defects in Wisconsin. These data are similar to those available through the National Birth Defects Prevention Network (NBDPN).

Below you will find some general information about birth defects and how they are related to environmental health. Each specific birth defect's page includes frequently asked questions about that defect; access those pages by clicking on the tab for "Which birth defects..." below.

Please contact the Tracking team if you have any questions.

Woman holding her pregnant belly

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What is a birth defect?

A birth defect is a problem that happens while the baby is developing in the mother’s body. Most birth defects happen during the first 3 months of pregnancy.

A birth defect may affect how the body looks, works, or both. It can be found before birth, at birth, or any time after birth. Most defects are found within the first year of life. Some birth defects, such as cleft lip or clubfoot, are easy to see. Other birth defects, such as heart defects and hearing loss, are found using special tests, such as x-rays, CAT scans, or hearing tests. Birth defects can vary from mild to severe.

Some birth defects can cause the baby to die. Babies with birth defects may need surgery or other medical treatments.  However, if babies receive the help they need, they often lead full lives.

Which birth defects will Wisconsin Tracking have data on?

As mentioned above, Wisconsin Tracking receives data from the Wisconsin Birth Defects Registry, but the registry is an opt-in system, meaning birth defect reporters (such as physicians) must get parental consent to report a birth defect. As a result, Wisconsin experts estimate about two in three birth defects are unreported. We are currently working with our partners to get more accurate data and will post them on our portal when they represent a more complete picture of birth defects in Wisconsin.

The Registry collects data for birth defects found in children from birth to 2 years of age. The reported birth defects were diagnosed or treated in Wisconsin by a physician, pediatric specialty clinic, or hospital. The defect must require medical or surgical intervention or interfere with normal growth and development. The Registry collects data for 87 reportable defects, and Wisconsin Tracking selected 10 to track.

The 10 were selected for the following reasons:

  1. These defects are included as part of the annual report for the National Birth Defects Prevention Network.
  2. Concerns from the public indicate a belief that these defects might be related to environmental exposures.
  3. These defects are quite severe.
  4. Given the physical nature of many of the defects, it is likely there will be consistent diagnoses, which makes the data more reliable and useful.

In the future, Wisconsin Tracking will report data to the National Environmental Public Health Tracking Network on the following 10 birth defects:

How common are birth defects?

About one in every 33 babies is born with a birth defect.¹ Every 4 ½ minutes, a baby is born with a birth defect in the United States.² In Wisconsin, nearly 2,000 babies are born with a birth defect each year.  

Some women have a higher chance of having a child with a birth defect. Women over the age of 35 years have a higher chance of having a child with Down Syndrome than women who are younger.

If taken when a woman is pregnant, certain drugs can increase the chance of birth defects. Also, women who smoke and use alcohol while pregnant have a higher risk of having a baby with certain birth defects. Other women have a higher chance of having a baby with a birth defect because someone in their family had a similar birth defect.

Women who want to learn more about their risk of having a baby with a birth defect can talk with a genetics counselor. Women can also talk about ways to prevent birth defects with their health care provider.

References:
1. Centers for Disease Control and Prevention. Birth defects.
2. Centers for Disease Control and Prevention. Facts about birth defects.

What causes birth defects?

We do not know what causes most birth defects. Sometimes they just happen and are not caused by anything that the parents did or didn't do. While we don’t always know what causes a birth defect, we do know some things increase the chances of a birth defect happening.

When during pregnancy do birth defects happen?

Birth defects happen before a baby is born. Most birth defects happen in the first three months of pregnancy, when the organs of the baby are forming. This is the most important stage of development. However, some birth defects happen later in pregnancy. During the last six months of pregnancy, the tissues and organs continue to grow and develop.

Are birth defects preventable?

A healthy pregnancy can help prevent birth defects, but not all birth defects can be prevented. Women who are pregnant or planning to get pregnant should talk to a health care provider. Care before birth can help avoid some problems and reduce the likelihood of birth defects. To learn more about preventing birth defects, visit the CDC’s page on guidance for preventing birth defects.

How are birth defects related to the environment?

Birth defects such as spina bifida, cleft lip/palate, gastroschisis, hypospadias, Down syndrome, and heart defects have all been linked to living near hazardous waste sites. Some birth defects have also been linked to disinfection by-products in drinking water.

The causes of most birth defects remain unknown. With the data collected through the National Tracking Program, researchers will be better equipped to study the relationship between birth defects and the environment.

Where can I learn more about birth defects?

Last Revised: September 10, 2019