You will be offered various antenatal screening and diagnostic tests during pregnancy. Find out what they can reveal about your health and the health of your baby here.
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 diagnosis (NIPD) or non-invasive prenatal testing (NIPT)?
In November 2016, following a clinical recommendation by the UK National Screening Committee, a non-invasive prenatal test for Down’s, Edwards’ and Patau’s syndromes, was approved.
From 2018, the NHS will offer women a non-invasive prenatal test (NIPT) screening test as an alternative to the invasive tests. The main advantages of NIPT are that it can be carried out much earlier in pregnancy compared to current tests and that the procedure does not carry any risk of miscarriage. The test only requires a blood test from mum, rather than having to take a sample directly from the womb as in other types of prenatal diagnosis, such as chorionic villus sampling (CVS) or amniocentesis.
Women can get false positive results though and it is likely that invasive testing will still be required to confirm a positive NIPT result. However, by introducing NIPT the number of women being offered and taking up the invasive test is likely to fall significantly.
There are currently private providers who offer NIPT (you may 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.