Usually performed between 14 and 20 weeks of pregnancy, amniocentesis can be used to diagnose many different gene and chromosome issues in the fetus including: Down syndrome; rare, metabolic disorders that are passed down through families; and other genetic abnormalities, like trisomy 18.

The procedure involves removing a small amount of fluid from the uterus. The amniotic fluid contains genetic information, which will help confirm or rule out any genetic abnormalities. This diagnostic test is often suggested for women with a family history of genetic disorders, who are more than 35 years old or who had an abnormal result on previous screenings. It's 99% accurate for diagnosing Down syndrome.