Why: To test for certain birth defects.
When: Usually between 15 and 20 weeks of pregnancy. Not recommended during the first trimester.
How: Using ultrasound as a guide, the health care provider inserts a thin needle through the woman's belly and uterus. A small amount of amniotic fluid (the fluid that surrounds the baby) is removed and tested.
Risks: A small risk of miscarriage (1 in 300 to 1 in 500). Some women have cramping, spotting or leaking of amniotic fluid after the procedure. Serious complications are uncommon.
For more information, read the March of Dimes fact sheet on amniocentesis.
August 2008
