What is a Birth Defect?
Major birth defects are congenital conditions present at birth that cause structural changes in one or more parts of the body. Major birth defects also have a very serious adverse affect on health, functional ability, or development.
Approximately one in thirty-three babies are born with a birth defect. Birth defects are also the leading cause for infant death - resulting in over one in every five infant deaths. Babies with birth defects have a higher chance of chronic illness and disability than babies born without birth defects.
Types of Birth Defects:
Structural Birth Defects are those in which a specific body part is missing or formed improperly. The most common type of structural birth defects are congenital heart defects. Other common structural defects include spina bifida, cleft palate, and clubfoot.
Metabolic Birth Defects are inborn problems in the body's chemistry. Generally, metabolic birth defects involve a missing or incorrectly formed enzyme. Babies born with metabolic birth defects do not generally have visible abnormalities but the defects are usually harmful or fatal. Common types of metabolic birth defects are Tay-Sachs disease and Phenylketonuria (PKU).
Defects Caused by Congenital Infections are the result of a maternal infection before or during the pregnancy. Cytomegalovirus (CMV) is the most common congenital infection and is sometimes associated with intellectual disability and hearing loss. Other types of congenital infections that may cause birth defects are rubella, syphilis, toxoplasmosis, and parvovirus.
Causes for Birth Defects:
Birth defects are defects that occur during gestation. Most birth defects develop within the first three months of pregnancy when the delicate organ systems are forming; however, others may develop later in pregnancy.
Most babies born with birth defects are born to two parents without obvious health problems or risk factors. A woman can do everything her doctor recommends and still deliver a child with a birth defect. According to the March of Dimes, 60% of birth defects have no known cause.
Genetic Birth Defects - Genetics play a role in certain birth defects. Every cell in the body has chromosomes containing genes that determine a person's unique characteristics. When a gene is missing or deleted, this can cause significant impairment.
- Dominant Inheritance - the faulty gene is passed down by one parent.
- Recessive Inheritance - two healthy parents pass down a faulty gene for the same disease to a child.
- X-Linked Defects - male children inherit disorders from their mother. A faulty X chromosome is more likely to cause disease or defect in men, as they only have one copy of the X chromosome (XY). X-linked disorders in female children may only have a mild form of the disorder, as they have an additional X chromosome to balance the faulty chromosome (XX).
Environmental Causes are those related to maternal health and exposure to chemicals or diseases. Certain infections (like rubella) can cause birth defects, as can maternal alcohol abuse or ingesting certain medications. Substances that harm the embryo or fetus are called teratogens.
Multifactoral Birth Defects are caused by a complex mixture of genetics, behaviors, and environmental causes.
Risk Factors for Developing Birth Defects:
While the precise cause for birth defects is unknown, certain risk factors do increase the likelihood of birth defects. Here are some of the risk factors for birth defects:
- Maternal age over 35 years old.
- Use of teratogenic substances during gestation.
- Maternal medical conditions like obesity and diabetes.
- Family members with a birth defect.
- Maternal smoking, alcohol use, or use of substances during pregnancy.
Recent research has shown evidence that males of advanced age or who have used substances during preconception may also contribute to a higher risk of children with birth defects.
Prenatal Diagnosis of Birth Defects:
Depending upon the type of defect, birth defects may be diagnosed prenatally or after birth. There are two types of prenatal tests available to assess potential birth defects - screening and diagnostic tests.
Screening tests are procedures performed to ascertain if a woman or her child have the potential to have a certain problem. Screening tests do NOT provide a specific diagnosis. Screening tests may give an elevated or abnormal result when nothing is wrong with the pregnancy, or (less often) give a normal result when something is wrong with the pregnancy.
During pregnancy, women are offered these screening tests to ascertain the risk for birth defects and other problems. These screening tests occur during each trimester of pregnancy.
First Trimester Screenings are given between weeks 11 and 14 of pregnancy and screen for heart or chromosomal disorders.
- Maternal Blood Screen - a simple blood draw that measures hCG and pregnancy associated plasma protein A (PAPP-A). High or low levels may indicate a chromosomal disorder in the fetus.
- Ultrasound Examination - may check for fluid behind the neck of the fetus (NT or nuchal fold). Increased levels may indicate a heart defect or chromosomal disorder.
Second Trimester Screenings - completed between weeks 15 and 20 to screen for certain birth defects.
- Maternal Seurm Screen (triple screen or quad screen) - a simple blood draw used to ascertain if there is an increased risk for fetal birth defects, including neural tube defects or chromosomal disorders.
- Anomaly Ultrasound - between 18-20 weeks of gestation, an ultrasound is completed to check the size of the fetus, identify birth defects or other structural problems with the fetus or the pregnancy.
If the results of a screening is abnormal, it's common to have these additional diagnostic tests to determine if birth defects or other problems are present. These tests are also offered to women with high risk pregnancies - women who've had a pregnancy with previous birth defects, women over 35, women who use certain medications, and women who have chronic diseases.
- High Resolution Ultrasound (also known as a Level II Ultrasound), usually performed between weeks 18-22 of pregnancy, can examine the fetus in greater detail to check for birth defects and other problems with the pregnancy.
- Chorionic Villus Sampling (also known as CVS), usually performed between weeks 10 and 12 of pregnancy, is the collection of a tiny piece of the placenta used to test for chromosomal or genetic disorders in the fetus. A CVS is generally offered after an abnormal result from a first trimester screening.
- Amniocentesis - between weeks 15 and 18 of pregnancy, a small amount of amniotic fluid is collected to measure the protein levels of the fetus, which may indicate certain birth defects. The fluid is also used to test for chromosomal disorders such as Down Syndrome and genetic disorders like cystic fibrosis and Tay-Sachs disease.
Defects That May Be Diagnosed Prenatally:
- Neural Tube Defects
- Down Syndrome
- Inherited Metabolic Disorders
- Congenital Heart Defects
- Gastrointestinal or Kidney Malformations
- Cleft Lip/Palate
- Birth Defects of the Limbs
- Congenital Tumors
- Other Chromosomal Abnormalities
How Can Birth Defects Be Prevented?
Certain birth defects can be prevented, while others cannot. Here are some things a woman can do before and during pregnancy to reduce the risks for birth defects:
- Take 400 micrograms of folic acid every day at least a month before pregnancy, as well as during pregnancy.
- Avoid alcohol, drugs and cigarettes.
- Learn how to prevent infections during pregnancy.
- Make sure chronic illnesses are under control (such as diabetes or hypothyroidism) before and during pregnancy.
- Discuss current medications and herbal supplements with a doctor to find out what is safe to take during pregnancy and what is not.
- Reach and maintain a healthy weight. Women who are obese before pregnancy are at greater risk for pregnancy-related complications, as well as serious birth defects for the fetus.
- Regularly see a doctor and receive ongoing prenatal care as soon as pregnancy is suspected.
- Discuss any vaccinations with a doctor - some are recommended during pregnancy and some are not.
Specific Birth Defects:
Click the links below to read on about common specific birth defects.
Neural Tube Defects - birth defects of the brain and spinal cord in which parts of the embryonic neural tube (later becomes brain and spinal cord) does not properly fuse together, allowing parts of the brain or delicate spinal cord to herniate outside of the body.
Encephalocele - rare neural tube defect in which a body defect in the skull allows part of the brain to herniate and develop outside of the skull.
Anencephaly - an incompatible-with-life neural tube defect in which a baby is born without parts of the brain and skull.
Spina Bifida - a type of neural tube defect in which the backbone that protects the spinal cord does not form properly and the spinal cord and nerves are damaged.
Down Syndrome - a mild-to-severe birth defect in which a baby is born with an extra chromosome.
Cleft Palate - a birth defect in which the roof of the mouth does not join together properly.
Congenital Heart Defects - a group of more than thirty-five disorders in which the structure of the heart is impaired, restricting normal blood circulation.
Cystic Fibrosis - chronic disease that causes the body to produce a thick mucus that impedes lung function, often leads to dangerous lung infections, interferes with pancreatic function, and obstructs natural digestive processes.
Tay Sach's Disease - an inherited, fatal autosomal recessive disorder.
If Your Baby Has a Birth Defect:
It's hard to get away from the images of happy mothers and healthy babies, but over 150,000 babies a year in the US alone are born with birth defects. These birth defects may range from mild to severe and may be discovered prenatally or not until birth.
Parents of children with birth defects will likely experience a number of emotions, feel overwhelmed by uncertainty and scared of the future.
Here are some other ways to handle having a child with a birth defect:
- Accept and acknowledge your emotions. Give yourself permission to feel your feelings and mourn the healthy child you were likely expecting. Talk about your feelings to your doctor, your partner, or a therapist who understands what you're going through.
- Seek Support. Find someone else who has been through the same thing. See if you can find a support group (ask your nurse or doctor) and get in touch with a community of people who truly understand what you're going through. Write it out for Band Back Together.
- Celebrate the child you do have. It's not the child you thought you'd have, but remember that the child you do have - enjoy the snuggles, cuddles and milestones. Send out birth announcements. Let other people enjoy your baby with you.
- Educate yourself. Pester your doctor with every question about the condition you can think of. Take notes. Find national organizations devoted to your child's condition and reach out. Find books related to the condition and learn. Find support groups and see what other people have experienced.
- Seek Early Intervention. A team of experts can meet with your child, assess needs, and get the child into therapies as soon as possible. Your doctor should be able to refer you to your local Early Intervention agency.
Additional Resources for Birth Defects:
March of Dimes - leading nonprofit organization for pregnancy and baby health. With chapters nationwide, the March of Dimes works to improve the health of babies by preventing birth defects, premature birth and infant mortality.
Zero to Three - a national nonprofit organization that informs, trains and supports professionals, policymakers and parents in their efforts to improve the lives of infants and toddlers.
National Dissemination Center for Children with Disabilities - a wealth of information on disabilities. They serve the nation as a central source of information on disabilities in infants, toddlers, children, and youth. Here, you’ll also find easy-to-read information on IDEA, the law authorizing early intervention services and special education. Our State Resource Sheets will help you connect with the disability agencies and organizations in your state.