Antenatal and newborn screening

Ultrasound scans use sound waves to build a picture of your baby in the womb. You will be offered a scan that produces a two-dimensional (2D) black and white image

The scans are painless and have no known side effects to women or babies. For most people, having a pregnancy scan is a happy event. But please be aware that ultrasound scans can detect serious health problems so try to be prepared for that.

All pregnant women and people are offered a scan at around 12 weeks to accurately date the pregnancy; this is usually your first scan and confirm how many babies you are carrying.   

The sonographer will use this scan to take measurements of your baby and estimate your baby’s due date (estimated date of delivery). It is the date from the scan that is used throughout your pregnancy, rather than going from your last period. You may choose to have first trimester screening for three chromosomal conditions, Down’s, Edwards’ and Patau’s Syndromes at the time of the dating scan and this will include a nuchal translucency (NT) measurement, which is part of the combined screening for Down’s syndrome, if you choose to have this screening.

Should your pregnancy be more advanced than 14+1 weeks but less than 20 weeks and you are unable to have this screen, you will be offered a Quadruple test for Down’s Syndrome.

A mid-pregnancy scan forms part of the antenatal screening programme that we offer.

It usually takes place at around 20 weeks and the main purpose of this scan is to look for abnormalities as it checks for 11 physical conditions in your baby. You may have heard it being referred to as an anomaly scan.  

During the scan, we take a careful look at your baby from head to toe. Usually, we learn that the baby appears to be healthy and is developing well.

However, sometimes we may find a problem. Some problems are quite common, and others are rare. A few of these problems are serious, but most are minor, and any problems identified will be explained in detail to you. 

Scans have their limitations. Sometimes we have to say there might be a problem but cannot say for certain. In a small number of cases, babies are born with abnormalities, even though no problem was identified by the scan.  

This scan is not designed to tell you the sex of your baby, but once all checks have been made the sonographer may be able to offer you the chance to find out if you are having a boy or a girl if requested. Please note this is not always possible and is not always 100% accurate.

Screening tests will not harm you or your baby, as far as we know the scans that we offer are safe for mother and baby. But there are some risks to consider. Some screening tests during pregnancy can lead to serious decisions for you.

For example, screening tests for Down’s syndrome comes with no risk, however if you are diagnosed with a high chance result, this can lead to difficult decisions about whether to have a diagnostic test that carries possible risk of miscarriage.

If the results of the diagnostic are positive, they can lead to a decision about whether you want to continue or end your pregnancy. Having further tests or termination will always be your decision, and health professionals will support you whatever you decide. You may want to think carefully about whether you want to have these screening tests or not.

Different screening tests will be offered at different times during pregnancy.

The screening test for sickle cell and thalassaemia should be offered by 10 weeks.

It’s recommended that screening blood tests for HIV, hepatitis B and syphilis should happen as early as possible in pregnancy too. This is so you can be offered specialist care and treatment to protect your health and reduce the chance of your baby getting infected if required. These blood tests should not be delayed until the first scan appointment.

You will be offered screening for Down’s syndrome around the time of your dating scan, which happens when you are around 11 to 14 weeks pregnant.

You will be offered screening for abnormalities at a mid-pregnancy scan when you are around 18 to 21 weeks pregnant.

This depends what the screening tests are looking for.

Yes

Screening tests for HIV, hepatitis B and syphilis are very accurate, and will tell for certain whether you have these infections.

If the test is positive, you’ll be offered further tests and examinations by specialist doctors to find out the treatment you need.

No

Screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome cannot say for certain whether your baby has the condition. It tells you if your baby has a lower or higher chance of having the condition.

If your baby has a higher chance of a condition, you’ll be offered another blood test known as Non-Invasive Pre-natal testing (NIPT) or a diagnostic test that gives a more definite “yes” or “no” answer Screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome: NIPT – GOV.UK (www.gov.uk).

Screening tests for sickle cell and thalassaemia will tell you for certain whether you’re a carrier or have these conditions. They will not tell you whether or not your baby has the condition.

If you or the baby’s father is a carrier or has the condition, you’ll be offered diagnostic tests to find out if your baby is affected.

No, you do not have to have the screening if you do not want to. It is a personal choice that only you can make, and it has to be the right decision for you and your family.

You can discuss each of the screening tests you are offered with your midwife or doctor before deciding. We will respect your choice.

Some of the screening tests you will be offered are recommended by the NHS, such as:

• Blood tests for infectious diseases
• Eye screening if you have pre-existing diabetes (not gestational diabetes)
• Newborn checks

This is because the results from these tests can help to make sure that you or your baby get urgent treatment for serious problems.

Before having any screening performed you will be asked to give consent before it is carried out, please make sure you understand – feel free to ask any questions.