Prenatal Tests
Throughout your pregnancy, you will get different medical tests which help our team find out how you and your baby are doing. They go hand in hand with your prenatal visits. Prenatal tests check to see if your baby has any health problems. They are detailed below.
Genetic Screening Tests
These include the nuchal translucency scan (done between 10 and 13 weeks of pregnancy) and the NIPT (non-invasive prenatal testing) which is done at any time after 10 weeks in the pregnancy. These are screening tests which means they cannot diagnose a genetic problem, only identify babies who might be at higher risk for genetic problems. A diagnostic test can be done to diagnose a problem. If you have an abnormal genetic screening test, we will offer you a diagnostic test including amniocentesis which carries a 1 in 300 risk for miscarriage.
We generally counsel women and families to consider what they will do with the information from any genetic screening test very carefully before deciding to do the test.
Carrier Screening
Carrier screening is a type of genetic test that can tell you whether you carry a gene for certain genetic disorders. When it is done before or during pregnancy, it allows you to find out the chances of having a child with a genetic disorder. Carrier screening is available for a limited number of diseases, including cystic fibrosis, fragile X syndrome, muscular dystrophy, and Tay–Sachs disease. Some of these disorders occur more often in certain races or ethnic groups. For example, Tay–Sachs disease is most common in people of Eastern or Central European Jewish, French Canadian, and Cajun descent. But anyone can have one of these disorders. They are not necessarily restricted to these groups.
Nuchal Translucency Scan
The ultrasound evaluation measures nuchal translucency (fluid beneath the skin behind the baby’s neck). This evaluation of the fetus is to assist in identifying significant fetal abnormalities. This ultrasound does not detect neural tube defects. It is important to realize that an abnormal result does not equate to having an abnormality, but rather serves a prompt to discuss further testing.
Non-invasive Prenatal Testing (NIPT)
We currently offer a test that was clinically validated in a population of pregnant women with increased risk for chromosomal aneuploidy, including one or more of the following: advanced maternal age (35 years and older), personal/family history of chromosomal abnormalities, fetal ultrasound abnormality suggestive of aneuploidy, positive serum screening test. NIPT is a laboratory-developed test that analyzes circulating cell-free DNA extracted from a maternal blood sample. The test detects an increased amount of chromosomal 21, 18, and 13 material. This test can be performed in the first or second trimester as early as 10-weeks gestation. The test is currently not covered by insurance for women who are at low risk for chromosomal abnormalities. If you do not have one of the risk factors this test, you may have to pay for this test out-of-pocket.
A Few Other Prenatal Tests We Recommend
One-Hour Glucose Test
This test is done at about 26-28 weeks of pregnancy (sometimes we ask women at higher risk for pregnancy-related diabetes to do an earlier test). You don’t need to be fasting for this test, or do any special preparation. We do advise against eating a high sugar meal just before your test. The day of the test, you are given the glucola drink when you arrive for your appointment. You need to finish the glucola drink in about 5 minutes, and be sure your blood is drawn exactly one hour after you finish the drink. Don’t eat or drink anything during that hour before you get your blood drawn. We recommend you bring a snack with you to the visit, so you can eat after your test is complete. If your blood sugar is high, we will notify you of the need to do a diagnostic test for gestational diabetes, known as the 3-hour glucose tolerance test (GTT). There is also the option of drinking the FRESH TEST for those who want an additive free and gluten free glucose drink that is made with just three ingredients: Organic Glucose, Crystallized Lemon and Organic Mint. The Fresh Test can be ordered online. www.diabetes.org/diabetes-basics/gestational/
Group Beta Strep Test (GBS)
About 20% of women are carriers for group beta strep. There are rarely any symptoms and women who are carriers don’t need any special treatment. However, a few infants who are exposed to GBS in labor can get sick, so we test all women for this bacteria between 35 and 37 weeks of pregnancy (unless they are planning a scheduled cesarean section). Using a small Q-tip swab, we will gently swab just inside your vagina, down your perineum, and barely into your anus. If you are found to be GBS positive, we will let you know and plan to give you intravenous antibiotics during labor, which helps to prevent the infant from getting ill. Even if you need antibiotics, the nurse can use a saline lock, so that you don’t have to be attached to an IV line during the entire labor.
You can find more information on GBS at the CDC website: www.cdc.gov/groupbstrep/about/fast-facts.html
👶 Download your personalized prenatal labs tracker here.