Birth defects

A birth defect is a problem that is present at birth and happens when a baby is developing in their mother’s body. Most birth defects happen in the first 3 months of pregnancy because that is when the organs are developing.

A birth defect may affect the way the body looks, works or both. Some birth defects (such as cleft lip) are easy to see, but others (such as heart defects or hearing loss) are found using special tests. Birth defects can vary from mild to severe.

If your baby is born with a birth defect or other health condition, they may need special care at birth and later in life. You will be able to talk to your baby’s healthcare team about any questions or concerns you have.

A child born with a birth defect can still lead a normal and healthy life. Although these children may have challenges that other people don’t have, they can still do everything most other people do.

Researchers have identified thousands of different birth defects, but some are much more common than others. There are two main categories of birth defects: structural (how the body is formed) and functional (how the body works). In some cases, birth defects are caused by a combination of factors, leading to both structural and functional problems.

Structural birth defects

Structural birth defects relate to problems with how part of the body is formed. Some of the more common or serious problems include: 

• cleft lip or cleft palate
• heart defects, such as missing or misshaped valves
• abnormal limbs, such as a clubfoot
• neural tube defects, such as spina bifida, anencephaly or other problems related to the growth and development of the brain and spinal cord. 

 Image credit: Canva

Functional birth defects

Functional, or developmental, birth defects are related to a problem with how a body part or body system works. They can lead to intellectual and developmental disability and can include:

• nervous system or brain problems, for example, Down syndrome and Prader-Willi syndrome
• sensory problems, such as blindness or deafness – see hearing loss in babies and children
• metabolic disorders – problems with certain chemical reactions in the body, such phenylketonuria and hypothyroidism
• degenerative disorders – these conditions might not be noticeable at first but steadily get worse over time, for example, muscular dystrophy.

For most birth defects, the cause is unknown, but it may be due to one of the following causes:

• Genetics – one or more genes might have a change or mutation that results in them not working properly, as in cystic fibrosis.
• Chromosomal problems – a chromosome or part of a chromosome might be missing or there may be an extra chromosome, as in Down syndrome.
• Not getting enough of certain nutrients. For example, not getting enough folic acid before and during pregnancy is a key factor in causing neural tube defects.
• Exposure to harmful substances such as alcohol, cigarettes or certain medicines.
• Infections during pregnancy, such as rubella.

Not all birth defects can be prevented. However, you can increase your chances of having a healthy baby by adopting a healthy lifestyle and managing health conditions before you become pregnant.

The following factors increase your risk of having a baby with a birth defect: lack of folic acid, drinking alcohol immediately before and while you are pregnant, smoking cigarettes, using drugs and taking certain medications during pregnancy, as well as some types of infection, obesity and uncontrolled diabetes.

If you are planning to become pregnant, make a PACT with yourself to take the following actions:

• Plan ahead and take 800mcg of folic acid every day. This can help prevent major birth defects of the developing brain and spine.
• Avoid harmful substances, including alcohol, cigarettes and other drugs, and food-borne bugs. These can all cause complications in pregnancy and birth defects. See alcohol and pregnancy and smoking and pregnancy.
• Choose a healthy lifestyle – try to achieve and maintain a healthy weight and keep diabetes under control. Obesity and poor diabetes control increases the chance of birth defects and other problems in pregnancy. See eating, drinking and watching your weight in pregnancy and pre-existing diabetes and pregnancy.
• Talk with your healthcare provider about any medications you are taking and any vaccinations you may need. Certain medications can cause serious birth defects if they are taken during pregnancy. Most vaccinations are safe during pregnancy and some vaccinations, such as the flu vaccine, are specifically recommended during pregnancy. See pregnancy and immunisation.