You will be offered various antenatal screening and diagnostic tests during pregnancy. Here's what they can reveal about yours and your baby's health...
What is antenatal testing? The antenatal screening tests offered to you during pregnancy can help you find out more about:
- the health of your baby before or after he is born and
- your own health.
Antenatal tests are optional, and it is your decision whether to accept or refuse any pregnancy screening.
Tests for your baby
There are different types of antenatal tests available during pregnancy: screening tests and diagnostic tests. These tests can help you find out if your baby has a condition that would cause a disability.
A screening test estimates your ‘chance’ of having a baby with a certain condition. It is used to show which women are more likely to have a baby with a particular disability, but it cannot tell you for certain whether your baby has a particular condition.
"Screening tests are usually either scans or blood tests and won’t affect your baby or threaten his development in any way (they are non-invasive)."
A pregnancy scan, or ultrasound scan uses high-frequency sound waves to create a moving image of your baby, his internal organs and your placenta. You will be able to see the image on a screen, and a picture is almost always available as a print out. A detailed anomaly scan is carried out at 18-21 weeks of pregnancy.
Blood tests involve taking a sample of the mother’s blood and testing it for markers (such as hormone levels). This can give information about the risks of certain conditions.
Find out more about pregnancy scans and screening in Foetal screening in pregnancy.
Diagnostic tests are used to find out whether or not your baby actually has a particular condition, such as Down’s Syndrome. The results from a diagnostic test will tell you if your baby does have a specific condition. Apart from the detailed ultrasound scan, diagnostic tests can affect your baby as they are ‘invasive’ and carry a small risk of miscarriage.
What is non-invasive prenatal testing or cell-free DNA testing?
In November 2016, following a clinical recommendation by the UK National Screening Committee, a non-invasive prenatal test (NIPT) for Down’s, Edwards’ and Patau’s syndromes, was approved.
From 2020, the NHS will offer women an additional screening test, called NIPT. The main advantages of NIPT is that it is more accurate than current screening tests, although it is still not diagnostic. Similar to other screening tests it does not carry a risk of miscarriage.
The test consists of a blood test from mum. At this stage in pregnancy her blood will also contain DNA from the placenta, which can be analysed to see if there is a higher chance of her baby having Downs, Edwards or Patau’s syndromes.
Women can get false positive and false negative results. Therefore, if you wish to know for certain, you still need to have an invasive test. However, by introducing NIPT, women will have a more accurate chance of knowing if their baby does or does not have Down syndrome.
There are currently private providers who offer NIPT (you might have heard of the Harmony Test, for example).
Screening for your health
Pregnant women are usually screened to check their own health, and for conditions that might affect their baby's health during pregnancy. These tests may include blood tests and urine tests.
Making a decision on antenatal testing
Before you make any decisions on which pregnancy scans or antenatal screening to accept, it is important that you (and your partner) think about the implications. You may find yourselves going through unnecessary worry. In the worst case, you may find you are asked to make a decision about whether or not to continue your pregnancy.
Page last updated: 17 March 2014
Our support line offers practical and emotional support in all areas of pregnancy, birth and early parenthood: 0300 330 0700. We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.
NHS Choices gives full information on the checks and tests offered in pregnancy.
Healthtalkonline offers shared experiences, videos and stories from 37 women and 8 couples from the UK. Topics include making decisions about screening, including those that have and have not ended the pregnancy.
Antenatal Results and Choices is a national charity that provides information to expectant and bereaved parents throughout and after the antenatal screening and testing process. Telephone helpline: 0845 077 2290
RAPID (Reliable Accurate Prenatal non-Invasive Diagnosis) is a five-year UK national programme funded by the National Institute for Health Research to evaluate early non-invasive prenatal diagnosis (NIPD).
RCOG (Royal College of Obstetricians and Gynaecologists) offers a guidance sheet about amniocentesis and chorionic villus sampling.