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.

The following pages have information about specific birth defects:
Cleft Lip and Cleft Palate
Down Syndrome (Trisomy 21)
Hypoplastic Left Heart Syndrome
Spina Bifida (without Anencephaly)
Tetralogy of Fallot
Transposition of the Great Arteries
Upper and Lower Limb Deficiencies

Information and Resources
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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 anytime 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, but others (such as heart defects or 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, but, if they receive the help they need, these babies often lead full lives.

  • What is WI EPHT focusing on within birth defects?
    • The WI EPHT receives data from the Wisconsin Birth Defects Registry. The Registry collects data for birth defects found in children from birth to two years of age that 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 to be reported to the registry. The Registry collects data for 87 reportable defects, but the WI EPHT selected 11 of the defects based on certain criteria listed below.

      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 the 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 that there will be consistent diagnoses that will make the data more reliable and useful).

      The following is a list of defects that the WI EPHT website provides data:
      * Anencephaly
      * Cleft Lip with or without Cleft Palate
      * Down Syndrome (Trisomy 21)
      * Gastroschisis
      * Hypoplastic Left Heart Syndrome
      * Hypospadias
      * Spina Bifida (without Anencephaly)
      * Tetralogy of Fallot
      * Transposition of the Great Arteries
      * Upper and Lower Limb Deficiencies

  • What is my chance of having a baby with a birth defect?
    • In the United States, about 3% of babies are born with birth defects. In Wisconsin, approximately 2,000 infants are born with a birth defect each year, impacting 3% of all births in Wisconsin as well. 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. To learn more about your risk of having a baby with a birth defect, you can talk with a genetics counselor. Also, to reduce your chances of having a baby with a birth defect, talk with your health care provider about any medicines that you take, do not drink alcohol or smoke, and be sure to take 400 micrograms of the B vitamin folic acid every day. It is the amount of folic acid found in most multivitamins.

  • 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. Many parents feel guilty if they have a child with a birth defect even if they did everything they could to have a healthy child. Sometimes the causes of birth defects are determined after the baby is born. Although it is very difficult to find the cause of a birth defect, there are some things might increase the chances of having a baby with a birth defect. The questions and answers that follow talk about some of these known risks.

      * Genetic factors - It can be a cause in some but not all cases. Changes in the genes can cause certain birth defects in infants. Genes tell the cells how to work in the body like our heart to beat, our stomach to digest food, our muscles to push and pull, and our brain to think. Genes combine with many other genes to make chromosomes. Changes in single genes, groups of genes, or entire chromosomes can sometimes cause birth defects. These genetic changes might be passed down from one or both parents, or they might happen in the infant while it is developing in the uterus. Sometimes environmental factors can cause changes in the genes.
      * Alcohol - Drinking alcohol during pregnancy can cause a baby to be born with birth defects and have disabilities, called fetal alcohol spectrum disorders. These disorders can cause birth defects of the heart, brain, and other major organs. There is no known amount of alcohol that is safe to drink at any time during pregnancy. For more information about fetal alcohol syndrome disorders, go to
      * Smoking - A woman who smokes while she is pregnant has a greater chance of having a premature (early) birth, a small baby, or a stillborn baby. Her baby has a greater risk of dying during the first year of life. Some birth defects that may be related to the mother’s smoking include cleft lip, cleft palate, clubfoot, limb defects, some types of heart defects, gastroschisis (an opening in the muscles of the abdomen that allows the intestines to appear outside the body), and imperforate anus (there is no opening from the intestines to the outside of the body to allow stool or gas to be passed).
      * Illegal drugs - A mother’s use of illegal drugs, or “street drugs,” can increase the chances she will have a baby that is small, premature, or have other health problems, such as birth defects. Women who use cocaine while pregnant are more likely to have babies with birth defects of the limbs, gut, kidneys, urinary system and heart. It is also important that women not use street drugs after they give birth because drugs can be passed through breast milk and can cause problems for a baby’s growth and development.
      * Exposure to the MMR vaccine or other vaccines - The MMR is a vaccine for measles, mumps, and rubella. If a woman gets one of these viruses while pregnant, it may cause her to have a miscarriage or to have a baby with birth defects. The MMR, like some other vaccines, is made with viruses that are alive but very weak. Because these viruses are alive, there is a very slight chance that they may cause harm to the baby. For this reason, a woman who may be pregnant should not get an MMR or other vaccine unless she is at high risk of getting a serious illness without it. She should talk about the risks and benefits of getting the vaccine with her doctor. A woman who has just gotten the vaccine and then learns she is pregnant should also talk with her doctor. Vaccines such as those for tetanus and hepatitis are made from dead viruses or parts of dead viruses and do not cause infection in the mother and should not harm the fetus. Guidelines for vaccinating pregnant women are available.
      * Infections - Some infections can cause temporary or permanent birth defects. Cytomegalovirus can temporarily cause such symptoms as liver or lung problems. It can also permanently cause problems such as hearing loss and seizures. Additional information about some infections are explained below.

         Listeria is a bacteria that can be found in contaminated foods. It can cause stillbirth, miscarriage, premature delivery, and health problems in your baby. A list of foods to avoid or to prepare carefully during pregnancy include luncheon meats, hot dogs, soft cheeses like feta, and meat spreads.

         Toxoplasmosis is caused by a parasite. If a baby is infected while in the womb, the baby may show no symptoms at birth, but may develop symptoms later in life, such as blindness or intellectual disabilities. It can be found in many items including cat litter, raw meat, unwashed or unpeeled fruit and vegetables. There are simple steps to prevent the spread of toxoplasmosis.

         Lymphocytic Choriomeningitis virus can be carried by wild mice and spread to pet rodents, like hamsters. A mother can be infected by the droppings of the infected animals if she inhales the dust while sweeping up the droppings or is bitten by an infected animal. It can cause stillbirth or severe birth defects to the baby.

         Sexually transmitted diseases can cause chronic liver disease, blindness, and other problems in the baby. Hepatitis B is a sexually transmitted disease that can be passed to the baby before birth to cause liver damage or liver cancer later in life. The disease is preventable for your baby by administering a vaccine at birth.

         Chickenpox is an infectious disease that increases the unborn baby’s risk of birth defects if a pregnant woman gets infected during her first or early second trimester of pregnancy. The birth defects could be limb atrophy, scarring of the skin, problems with the central nervous system (brain and spinal cord) and eye abnormalities. Prevention measures can be taken by pregnant women to reduce their risk of getting chickenpox.

         Group B Streptococcus is a bacteria that comes and goes from the body naturally. Unfortunately, it can transfer to the baby during childbirth possibly causing infections in the newborns, including pneumonia (lung infection), sepsis (blood infection), meningitis (infection of the lining of the brain and spinal cord) and other problems. Sadly, many infants can die or have serious long-term effects from a GBS infection. Steps can be taken during childbirth to reduce the risk of exposure to the baby.

  • When during pregnancy do birth defects happen?
    • Birth defects happen before a baby is born. Inherited or genetic factors; exposure to drugs and/or alcohol; inadequate folic acid; and a woman’s illness during pregnancy can cause birth defects. Most birth defects happen in the first 3 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.

  • How can birth defects be prevented?
    • A healthy pregnancy can help in your prevention of birth defects. Here are steps to take prior and during your pregnancy.

      * Prior to becoming pregnant
      * See your health care provider before getting pregnant
      * Get any medical condition (obesity, diabetes, seizures, etc.) under control before getting pregnant
      * Take a vitamin with 400 micrograms of folic acid daily
      * During pregnancy
      * Get plenty of rest
      * Exercise moderately
      * Eat a well-balanced diet
      * Continue to take a vitamin with 400 micrograms of folic acid daily
      * Avoid contact with chemicals and other things in the home and workplace that may harm an unborn baby
      * Avoid alcohol, tobacco, and street drugs
      * Talk with your health care provider before taking any over-the-counter drugs

      If you are planning to get pregnant or you are already pregnant, one of the most important things you can do is see your health care provider. Prenatal (before birth) care can help avoid some problems and reduce other problems that can be found early in pregnancy and monitored and treated before birth. Unfortunately, not all birth defects can be prevented, but a woman can take some actions that increase her chance of having a healthy baby. Many birth defects happen very early in pregnancy, sometimes before a woman even knows that she is pregnant. Remember that about half of all pregnancies in the United States are not planned. The CDC provides a list of items to consider during pregnancy.

All external hyperlinks are provided for your information and for the benefit of the general public. The Department of Health Services does not testify to, sponsor, or endorse the accuracy of the information provided on externally linked pages.


Last Revised: January 28, 2014


Data Query

Access the data about specific birth defects in the WI EPHT online database. For more information about the birth defects data, go to the data details below to learn about interpreting the data.

Data Details

What is the data source?

The website provides data from the Wisconsin Birth Defects Registry, which is maintained by the Birth Defect Prevention and Surveillance program, Wisconsin Department of Health Services.

How does WI EPHT measure birth defects?

The WI EPHT website includes the following measures:

  • Prevalence rate of live births by geography
  • Number of birth defects by geography

What are some considerations for interpreting the data?

While significant effort is made to ensure the accuracy and completeness of the data, there are limitations that are listed below:

  • The Wisconsin Birth Defects Registry does not currently receive reports from all providers in the state. Thus, the numbers presented here represent only a subset of the actual cases.
  • Reporters have up to two years to provide data to the registry, so some cases from the most recent years may not yet be included in the registry.

There are many factors that can contribute to a disease and should be considered when interpreting the data. Some of these include:

  • Demographics, e.g., race, gender, age
  • Socioeconomic Status, e.g., income level, education
  • Geographic, e.g., urban vs. rural
  • Changes in the medical field, e.g., diagnosis patterns, reporting requirements
  • Individual behavior, e.g., diet, smoking