Skip to content
My WebMD Sign In, Sign Up

Genetics

Font Size

Prenatal Screening and Testing

There are two types of prenatal genetic tests: screening and diagnostic.

  • Screening tests show the chance that a developing baby (fetus) has a certain genetic condition. It can't tell for sure that your baby has a problem. If the test result is "positive," it means that your baby is more likely to have that condition. So your doctor may want you to have a diagnostic test to make sure. If the screening test result is "negative," it means that your baby probably doesn't have that genetic condition. But it doesn't guarantee that you will have a normal pregnancy or baby.
  • Diagnostic tests show if the developing baby has a certain genetic condition.

Examples of tests used for prenatal screening include:

If prenatal screening test results show an increased risk of problems, further diagnostic genetic testing (karyotype) can be used to examine the size, shape, and number of chromosomes. A karyotype can be done on cells taken from the placenta (chorionic villus sampling) in the late first trimester or from the amniotic fluid (amniocentesis) in the second trimester. Extra, missing, or abnormal positions of chromosome pieces can cause problems with growth, development, and body functions.

1

WebMD Medical Reference from Healthwise

Last Updated: November 03, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
Next Article:

Hot Topics

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

feet
Solutions for 19 types.
row of colored highlighter pens
Tips for living better.
oatmeal and eggs
The best and worst for you.
neti pot
6 steps for nasal irrigation.
MS Overview
Recognizing symptoms.
stressed working woman
And how to fix them?
woman walking in fog
12 tips for managing your disease.
Healthy Snack
13 delicious options.
Woman running
10 ways to boost your metabolism.
lone star tick
How to identify that bite.
young woman in sun
What to watch for.
Colored x-ray of tooth decay
What are the top ones?

Women's Health Newsletter

Find out what women really need.