Chromosome analysis—also known as karyotype—is a test to find the size, shape, and number of chromosomes in a sample of body cells. Chromosome analysis can be done on blood, tissue, or cells from amniotic fluid (the fluid that surrounds the baby in the womb).

Extra or missing chromosomes, or abnormal positions of chromosome pieces, can cause problems with a person's growth, development, and body functions. Chromosome analysis can help find out if:

• The chromosomes of an adult have an abnormality that can be passed on to a child.
• A chromosome problem is preventing a woman from becoming pregnant or causing her to miscarry.
• A chromosome problem is present in a baby.
• Chromosomal problems may have caused a baby to be stillborn.
• The cause of a birth defect or disability is a chromosomal defect.