Your 20-week scan: What you need to know

What you need to know about your 20-week scan

As exciting and nail-biting as it can be, your baby's 20 week scan is the most in-depth health check your baby will have during your pregnancy.

Your scan provides the very best opportunity to check for heart defects before birth, so at your 20 week scan your sonographer will be looking to see if your baby's heart is growing normally.

Your sonographer will also be examining many other elements of your baby's development including general growth, their brain and face, spine and kidneys.

Checking a baby's heart can be difficult and getting good images might prove tricky but here are some of the things your sonographer will be looking for:

• They'll look for five different views of the heart to see if everything looks normal at this stage
• All four chambers of the heart (see below)
• If the heart is the right size, in the correct place, and pointing in the right direction
• If the baby's valves and chambers are working together
• If the two vessels leaving the heart cross each other as they exit, like they should do
• If the cross in the heart where the walls and values meet is intact and working properly

Do lots of babies have heart defects?

Fortunately the majority of babies are born with a healthy heart, but heart defects are the most common congenital birth defect in babies.

Early diagnosis of heart defects can give babies a better chance and means that the right medical experts can be on hand at birth, treatment can begin as soon as possible and parents can start getting the support they need from the beginning.

What is CHD?

CHD stands for Congenital Heart Disease, which is when something goes wrong when a baby's heart is formed. One in every 125 babies is born with a heart defect. Every year in the UK, around 4,000 babies have a heart operation before their first baby. But every year more than 1,000 of these newborns leave hospital with an undetected heart condition that their parents and doctors don't even know about.

While the vast majority of babies are born healthy, sometimes the sonographer will suspect a problem and refer you to a specialist. Sometimes the sonographer won't be able to see everything they need to check - possibly because of the position of the baby - and you may need a repeat scan.