Amniocentesis is a test that may be done during pregnancy to check for fetal abnormalities (birth defects) such as Down syndrome, cystic fibrosis or spina bifida. A thin needle is used to take a small amount of amniotic fluid from the sac in the uterus surrounding a fetus. Possible risks include infection, injury to the baby or miscarriage.

Amniocentesis is a prenatal procedure that your doctor may recommend you have during pregnancy. The test checks for fetal abnormalities (birth defects) such as Down syndrome, cystic fibrosis or spina bifida. In most cases, the results are normal. Amniocentesis is performed between 16 and 20 weeks into the pregnancy. By around this time, the developing baby is suspended in about 130ml of amniotic fluid, which the baby constantly swallows and excretes. A thin needle is used to withdraw a small amount of this fluid from the sac surrounding the fetus. The fluid is examined to obtain information about the baby – including its sex – and to detect physical abnormalities such as Down syndrome or spina bifida. Amniotic fluid samples can also be DNA tested to identify a range of genetic disorders, such as cystic fibrosis and fragile X syndrome. Amniocentesis is only performed on women thought to be at higher risk of delivering a child with a birth defect. Discuss with your doctor or obstetrician whether amniocentesis is right for you.

Problems detected by amniocentesis

• Down syndrome
• Neural tube defects, such as spina bifida
• Genetic disorders – amniotic fluid samples can be DNA tested to identify a range of genetic disorders, such as cystic fibrosis and fragile X syndrome.