When you fall pregnant, and for some even prior to that, you’ll be getting all sorts of blood tests, ultrasounds and other medical procedures. So after the initial blood and urine test to confirm your pregnancy at 12 weeks you will be offered some more screening tests.
Types of 12 week pregnancy tests
There are two types of screenings that will be offered to pregnant women to be done at 12 weeks. The Non-invasive prenatal testing (NIPT) and the combined first trimester screening which includes an ultrasound.
What is the NIPT?
The NIPT is a test that looks at your baby’s genetics for chromosomal abnormalities, it will tell you the likelihood of the bub having Down Syndrome, Edwards Syndrome or Patau Syndrome. The mother’s blood is tested and will contain some DNA from the baby’s placenta. It is an optional screening test.
The results you receive are not definitive, but rather reported as a probability. For example, a low likelihood result would show that a one in 1000 chance that your baby has an abnormality. A very high result would be a one in two chance that your baby has an abnormality.
If your test results show a high likelihood of an abnormality it is likely that your doctor will recommend a diagnostic test such as a amniocentesis or CVS.
It is currently much more accurate than the combined first trimester screening and can be done at any point during the pregnancy after 10 weeks.
However, most obstetricians will recommend that as well as the NIPT, an ultrasound should also be done at 12 weeks to see how the baby is developing.
While this screening is most accurate, it is also the most expensive of the screenings. It is not covered by Medicare or private health insurance in Australia.
What is the combined first trimester screening?
This test will combine a blood test with the results of an ultrasound and the age of the mother to tell you the likelihood of the baby having chromosomal abnormalities, particularly Down Syndrome.
The test will need to be done after week 11 but before week 14. Like the NIPT tests, it is optional.
Two pregnancy-specific substances in the mother’s blood are tested — pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin (HCG), and in the ultrasound the nuchal translucency is measured. Nuchal translucency is measures the clear space in the back of the baby’s neck.
Results for the screening are given as positive, negative but also as a probablity (e.g. 1 in 1000 risk of carrying a Down Syndrome baby)
Although you may receive low-risk results, that doesn’t guarantee that your baby won’t be born with Down Syndrome.
This test should be covered by Medicare or your private health insurance.
What to do with the results
It is important for your doctor or midwife to explain the test results to you and should they come out positive, genetic counselling should be offered. For more information on raising children with Down Syndrome can be found here.
What to consider before having the 12 week pregnancy tests
What will you do with the results? This will be different for everyone. Some people are happy to continue a pregnancy, regardless of the test results, however they would like to know of any issues in advance to be prepared and informed. Other people choose to not do the 12 week pregnancy tests to avoid needing to make a difficult decision.