Beyond the Ultrasound: 4 Common Prenatal Tests
- July 17,2018
During pregnancy, tests performed on mother and baby fall into two main categories: screening and diagnostic. Screening tests are non-invasive and indicate the likelihood that a woman may have a baby with certain conditions. Diagnostic tests give more definitive results, but are invasive and therefore optional. Your doctor will discuss which, if any, diagnostic tests are appropriate given the specifics of your pregnancy.
Because diagnostic tests are less common and typically only conducted when there is a specific reason, this article focuses on screening tests.
Screening tests are generally a simple blood draw for mom, conducted at various points during pregnancy with a focus on different measurements. For most women, the outcome will be an "all clear" test result.
First trimester screen (10-14 weeks)
Your first OB-GYN visit during pregnancy will include a host of tests and questions related to your health and medical history. When you're a little farther along, your doctor may offer the first in a series of tests that can help determine the risk of having a baby with certain chromosomal abnormalities. These genetic screenings are optional.
The first trimester screen includes a blood draw that measures the levels of two different substances: the protein PAPP-A and the hormone hCG. Both of these substances are found in the blood of all pregnant women. However, abnormal levels of these substances are associated with certain disorders, such as Down Syndrome.
Multiple marker test (15-20 weeks)
This test uses a sample of the mother's blood to check the levels of specific hormones and proteins. In the quad screen multiple marker test, four specific substances are measured:
1. The protein AFP
2. The hormone hCG (same as in the first trimester screening)
3. The hormone Estriol
4. The hormone Inhibin A
Again, all of these occur naturally in the blood of pregnant women. The test checks for abnormal levels that could indicate a risk for certain birth defects or disorders. Results from this multiple marker test can be combined with the first trimester screening results for a more accurate indication of risk. Like the first trimester screen, this genetic screen is an optional test.
CBC Blood Test (24-26 weeks)
A simple blood draw to check on mom's health, this test looks at iron levels, vitamin D status, and thyroid function. All of these should be within the optimal range to make sure your pregnancy progresses smoothly.
Glucose Screening (24-28 weeks)
This screening tests mom for gestational diabetes, a short-term form of diabetes that may develop during pregnancy. The test requires that you drink a sugary liquid. An hour after you finish the drink, your doctor will draw blood and test for any indication that your body isn't processing sugar well enough. Gestational diabetes can be managed, but if it goes undiagnosed it may cause pregnancy complications or long-term health risks for the baby.