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.
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: