Description

Test Criteria

This test is most often done between the 15th and 22nd weeks of the pregnancy. It is most accurate between the 16th and 18th weeks.

A

 taken and sent to the lab for testing.

The test measures levels of 4 pregnancy hormones:

• Alpha-fetoprotein (AFP), a protein produced by the baby
• Human chorionic gonadotropin (hCG), a hormone produced in the placenta
• Unconjugated estriol (uE3), a form of the hormone estrogen produced in the fetus and the placenta
• Inhibin A, a hormone released by the placenta

If the test does not measure levels of inhibin A, it is called the triple screen test.

To determine the chance of your baby having a birth defect, the test also factors in: