Safety of chorionic sampling vs. Amniocentesis for prenatal diagnosis of chromosomal abnormalities?

Risks. The risk of pregnancy loss has been looked at in four randomized studies of cvs vs. Amniocentesis. All four studies show that both procedures have about the same risk of pregnancy loss. About 1 in 1600. Another cvs study showed that losses in a group of women who had the procedure were equal to losses in a group of women who didn't have the procedure. A loss may not be related to the procedure.