Prenatal screening tests can help identify if you’re at greater risk for having a baby with a birth defect, but with all the different types of screening options available, choosing with one is best for you can seem overwhelming.
“For couples undecided on having prenatal testing done, I first review with them their estimated risk for chromosomal abnormalities based on their age - the younger the patient, the lower the risk,” says Suzanne Hall, M.D., Beaumont OB/GYN. “Then, I have them consider what a positive test would mean to them, and their next steps in pregnancy management. This informational discussion helps some patients in their decision to pursue prenatal testing or not.”
If your doctor recommends a prenatal screening and you’re unsure where to start, here’s a guide to your five options:
FIRST TRIMESTER SCREENING
What it is
During this screening, an ultrasound is done between the beginning of the 11th week and then end of the 13th week of pregnancy. The ultrasound measures the thickness of the nuchal translucency, a space on the back of the baby’s neck.
In addition, a blood sample is taken from you to measure the amount of two chemicals – pregnancy associated plasma protein-A, or PAPP-A, and human chronic gonadotropin, or hCG.
What it screens for
The results from the screening estimate the chances your child is at risk of Down syndrome, or Trisomy 18, otherwise known as Edwards syndrome.
QUAD SCREEN
What it is
During a quad screening, a blood sample is taken from you between 15 and 20 weeks of pregnancy. The sample is used to measure four chemicals – hCG, AFP, uE3 and inh-A.
What is screens for
The results estimate if your child is at risk for Down syndrome, Trisomy 18, open neural tube defects or Smith-Lemli-Opitz syndrome.
SERUM INTEGRATED SCREEN
What it is
In a serum integrated screen, a blood sample is taken during the first trimester to measure the amount of PAPP-A. Then, a second blood sample is taken in the second trimester to measure the concentration of AFP, hCG, uE3 and inh-A.
What it screens for
Once taken, the five chemicals will be integrated into a single screening result to estimate your baby’s risk of Down syndrome, Trisomy 18, open neural tube defects or Smith-Lemli-Opitz syndrome.
FULL INTEGRATED SCREEN
What it is
A full integrated screen combines options A and B. Just like in option A, an ultrasound is done to determine the thickness of the nuchal translucency. A blood sample is then taken to determine the amounts of PAPP-A, and the four chemicals discussed in option B.
What it screens for
The NT thickness and the five chemicals in your blood are then combined into a single screening to estimate your baby’s risk of Down syndrome, Trisomy 18, open neural tube defects and Smith-Lemli-Opitz syndrome.
SEQUENTIAL SCREEN
What it is
This option is broken into two parts. In part one, the NT measurement, PAPP-A amounts and your age are combined to calculate your baby’s risk of Down syndrome and Trisomy 18. This test is done between 11 and 13 weeks of your pregnancy.
What it screens for
After your tests, if your first trimester risk for Down syndrome and Trisomy 18 hasn’t increased, you’ll be asked to come back for a blood draw during the second trimester, which is combined with the original tests to determine the risk of your baby having Down syndrome, Trisomy 18, open neural tube defects or Smith-Lemli-Opitz syndrome.
Which screening is best for you depends on when you begin the testing and when you’d like results. You are encouraged to discuss the tests with your health care provider before you decide whether you’d like to be screened.
“Certain family history of chromosomal abnormalities, and advance maternal age, may put a patient at a higher risk for a chromosomal abnormality,” says Dr. Hall. “However, all pregnant women should be offered screening before 20 weeks gestation.”