Genetic Testing in Pregnancy
The number of genetic tests available in pregnancy is increasing and it can be confusing to work out which ones you need. Different tests are offered at different stages of pregnancy and look for different things.
Some genetic tests in pregnancy aim to prevent a baby being born with an inherited disease. Others aim to identify conditions early so something can be done.
Many of the inherited diseases looked for are rare and there is usually no family history, so it usually comes as a shock to parents to find they are silent carriers for a condition, or if their baby is affected.
The newest genetic test in pregnancy is an early detection test for serious medical issues in newborns that is done after your baby is born. It looks for 50 treatable conditions in the first few days of life so that treatment can be started early to prevent health problems.
Genetic tests before you fall pregnant
DNA tests before you become pregnant help you work out if you are a silent carrier for an inherited condition, and the risk that your baby might be born with it. These types of test are called carrier screening tests or preconception carrier screening. Some of these tests screen for the 3 most common genetic conditions in Australia, others test for hundreds of conditions or even more.
A lot of GPs don’t know about these tests because they are not commonly done in Australia. Specialists now recommend that this type of testing be offered to all women before pregnancy or during early pregnancy.
Most inherited conditions are rare but there are hundreds of them so together they are relatively common, affecting about 1-2% of all births and causing about 20% of all infant deaths.
If you know whether you are a silent “carrier” for one of these conditions then you can be better informed about the risk your baby might have one of these problems and do something about it. If your baby is at a high risk of having one of these problems you can think about doing IVF or something else to reduce the risk.
Here is a link to Rachael’s story about her daughter Mackenzie, who was born with a rare genetic condition and why she thinks this type of carrier testing is the most important test in pregnancy.
Genetic tests during pregnancy
Carrier screening tests (described above) can be done early in pregnancy if they were not done beforehand.
Other genetic tests done in early pregnancy are called Non-Invasive Prenatal Screening or Non-Invasive Prenatal Testing. The Harmony or Panorama test are the most common of these tests. These are blood tests done on the mother that look at the baby’s DNA to see whether your baby has Down syndrome or 2 other genetic conditions.
Chorionic Villus Sampling and Amniocenteses are tests that are sometimes done in pregnancy. A small sample from the placenta or amniotic fluid is taken and genetic testing is done on the baby’s DNA to see whether your baby might have a genetic problem. A link to more information about this type of genetic testing is found here.
Genetic tests for babies after they have been born
In Australia, most babies when they are about 48 hours old have a genetic test called the heel prick blood test. This is called newborn screening or neonatal screening and it looks for about 25 inherited conditions in babies before they get sick. It is an early detection test, so that treatment can be started to prevent serious genetic diseases.
It is free of charge to parents through the public health system in Australia because it is so important. Here is a link to a good webpage that explains this type of genetic test.
There is a new early detection test for an extra 30 conditions not tested in the public system. It is done at the same time as the heel prick test, but is a painless mouth swab. Click here for more information about the test. The test is only available through Genepath and offers parents great peace of mind, knowing they have done everything to give their child the healthiest start to life possible. After all, prevention is better than cure.
