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Second trimester: Tests you may have

The second trimester is by far the easiest for most women, but that doesn't mean you're guaranteed a complete holiday from needle sticks. Depending on your age and medical history, your doctor may request these tests for you.

Multiple marker screen: This blood test looks for proteins produced by your baby and by the placenta. This common test can rule out some brain or spinal disorders.

Amniocentesis: An amniocentesis is a test of your amniotic fluid, which is the fluid that the fetus floats in. This test can detect or rule out certain birth defects. Learn about having an amniocentesis.

Antibody screen: This blood test checks for certain antibodies in your blood from previous pregnancies or from infections such as measles. It measures antibodies against specific blood proteins and looks for previous maternal exposure to blood types other than your own.

  • If your test comes back "positive" you may more testing.
  • If you have Rh negative blood, you may receive a shot to prevent Rh incompatibility.

You may have had an antibody screen during your first prenatal visit. But the test may be repeated at 24 to 28 weeks with the one-hour glucose screen for gestational diabetes. (See information below.)

Testing for gestational diabetes

One-hour glucose screen: During the second trimester, your doctor will want to test your blood to find out if you may have gestational diabetes. Gestational diabetes begins during pregnancy, and usually goes away after the baby is born. About 4 percent of pregnant women develop this condition.

For a glucose screen, you'll have your blood sugar level checked after 12 hours of fasting or you will drink a very sweet drink. An hour later, your blood will be drawn. If the result is positive, then you'll probably have the glucose tolerance test.

Three-hour glucose tolerance test: You eat normally the day before and do not eat during the night before this three-hour test. (It's a good idea to bring a book or magazine to read or something else to do with you to the doctor's office.)

The test involves four blood draws and one sugary drink:

  • Your first blood draw provides a fasting glucose level.
  • After your first draw, you'll have a sugary drink.
  • After you take the drink, your blood will be drawn once an hour for three hours.

If you have gestational diabetes, your doctor or other health care provider will talk with you about your treatment plan. You'll need to work out a food plan and an exercise routine. You may have to take medication, too.

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Source: Allina Health's Patient Education Department, Beginnings: Pregnancy, Birth and Beyond, fourth edition, ISBN 1-931876-14-2

First published: 03/07/2000
Last updated: 10/14/2007

Reviewed by: Michael Slama, MD, Allina Health Mercy Women's Health Clinic