Amniocentesis is a test done during pregnancy that removes some amniotic fluid for testing. Amniocentesis is done to look for birth defects and genetic disorders. It is usually offered mainly to women with a higher-risk pregnancy, including those over 35. Some disorders that amniocentesis can find include Down syndrome, sickle cell disease, cystic fibrosis, Tay-Sachs disease, and more. The test is usually done between the 15th and 20th weeks of pregnancy. Follow the links below to find WebMD's comprehensive coverage about why amniocentesis is done, what it tests for, who should have it, and much more.