A medical test that involves withdrawing a sample of fluid from the amniotic sac surrounding the fetus in the abdomen of the pregnant woman.

Amniocentesis is a procedure used to detect the presence of genetic disorders such as Down syndrome and spina bifida in a fetus. The primary tool for prenatal diagnosis, it is also used to determine the maturity level of a potentially premature baby. Amniocentesis is normally performed in the 14th-16th weeks of pregnancy in women considered to be at risk of Down syndrome or other problems.

Prior to the development of amniocentesis in the 1950s, there was no way to detect whether a baby might be born with serious health problems. Amniocentesis has changed the nature of pregnancy by offering greater information about the fetus and creating more decisions for the parents. If problems exist with the fetus, the pregnant woman must decide if...