Hormone Inhibin A
The inhibin A test is done to measure the amount of this
hormone in a pregnant woman's blood to see if the baby
Down syndrome. Inhibin A is made by the
placenta during pregnancy.
The level of
inhibin A in the blood is used in a
maternal serum quadruple screening test. Generally
done between 15 and 20 weeks, this test checks the levels of four substances in
a pregnant woman's blood. The quad screen checks alpha-fetoprotein (AFP), human
chorionic gonadotropin (hCG), a type of estrogen (unconjugated estriol, or
uE3), and the hormone inhibin A. The levels of these substances—along with a
woman's age and other factors—help the doctor estimate the chance that the baby
may have certain problems or birth defects.
- Pregnancy: Should I Have Screening Tests for Birth Defects?
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Why It Is Done
A test for inhibin A is done in
addition to other tests to see if there is a chance of
chromosome problems, such as Down syndrome.
How To Prepare
You do not need to do anything before
you have this test.
How It Is Done
The health professional drawing blood
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
You may feel anxious while awaiting results of a maternal
serum quad test done to determine the health of your unborn baby.