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Why it's offered

Chorionic villus sampling (CVS) is only offered to pregnant women with an increased risk of having a baby with a genetic or chromosomal condition. It can diagnose a range of conditions.

You'll be offered CVS if your test results or medical or family history suggest you have a higher chance of having a baby with a genetic or chromosomal condition.

You do not have to have the test if it's offered. It's up to you to decide whether you want it.

What conditions can CVS detect?

CVS can be used to diagnose a number of conditions, including:

CVS cannot detect neural tube defects. These are birth defects affecting the brain and the spinal cord, such as spina bifida, which can usually be detected with an ultrasound scan.

Deciding whether to have CVS

If you're offered CVS, ask your doctor or midwife what the procedure involves and what the risks and benefits are before deciding whether to have it.

You may also find it helpful to contact a support group, such as Antenatal Results and Choices (ARC).

ARC is a charity that provides information, advice and support on all issues related to screening during pregnancy.

Reasons to have CVS

CVS will usually tell you for certain if your baby will or will not be born with any of the conditions that were tested for.

You might find that your baby does not have the condition screening tests said they might have, which can be reassuring.

But if the test confirms that your baby does have the condition they were tested for, you can decide how you'd like to proceed.

Read more about the results of CVS for more information.

Reasons not to have CVS

There's a risk of miscarrying the baby. Up to 1 out of every 100 women who have CVS will miscarry.

You may feel this risk outweighs the potential benefits of the test.

Find out more about the risks of CVS

Some women choose to have an alternative test called amniocentesis later in their pregnancy instead.

Some women decide they'd rather find out if their baby has a genetic condition when their baby is born.