Birth Defects

What are birth defects?

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

A birth defect may affect how the body looks, works, or both. Some birth defects, like cleft lip or neural tube defects, are structural problems that can be easy to see. Others, like heart defects, are found using special tests. Birth defects can range from mild to severe. How a birth defect affects a child's life depends mostly on which organ or body part is involved, and how severe the defect is.

What causes birth defects?

For some birth defects, researchers know the cause. For many others, the exact cause is unknown. Most birth defects are thought to be caused by a complex mix of factors, which can include:

• Genetics. A gene may have a change or mutation that stops it from working properly — for example, in Fragile X syndrome. With some defects, a gene or part of a gene is missing.
• Chromosomal problems. A chromosome or part of a chromosome may be missing (as in Turner syndrome) or there may be an extra chromosome (as in Down syndrome).
• Exposure during pregnancy to medicines, chemicals, or other toxic substances. For example, alcohol use in pregnancy can cause fetal alcohol spectrum disorders.
• Infections during pregnancy — for example, rubella or Zika virus infection can cause serious defects.
• Lack of certain nutrients. Not getting enough folic acid before and during pregnancy is a key cause of neural tube defects.

Who is at risk of having a baby with birth defects?

Certain factors may increase the chance of having a baby with a birth defect, including:

• Smoking, drinking alcohol, or using recreational drugs during pregnancy
• Having certain medical conditions before or during pregnancy — such as obesity or uncontrolled diabetes
• Taking certain medicines during pregnancy
• Having a family member with a birth defect (a genetic counsellor can help you understand your risk)
• Being an older mother, typically over 34 years of age

How are birth defects diagnosed?

A doctor can diagnose some birth defects during pregnancy using prenatal tests — which is one reason regular antenatal check-ups are so important.

Other birth defects may not be found until after the baby is born. Some — like club foot — are obvious right away. Others may only be picked up through newborn screening, or later, when the child develops symptoms.

What are the treatments for birth defects?

Children with birth defects often need special care and treatment. Because the symptoms and problems vary, so do the treatments — possibilities include surgery, medicines, assistive devices, physical therapy, and speech therapy.

Children with birth defects often need to see several specialists. Your child's primary doctor can help coordinate this care.

Can birth defects be prevented?

Not all birth defects can be prevented, but you can increase your chance of having a healthy baby by taking these steps before and during pregnancy:

• Start antenatal care as soon as you think you might be pregnant, and see your doctor regularly through pregnancy.
• Take 400 micrograms (mcg) of folic acid every day. Ideally, start at least one month before you conceive.
• Don't drink alcohol, smoke, or use recreational drugs.
• Talk to your doctor about any medicines you are taking or thinking about taking — prescription, over-the-counter, and herbal or dietary supplements.
• Learn how to prevent infections during pregnancy.
• If you have any medical conditions, try to get them well-controlled before pregnancy.