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