The Act of Giving Birth-Prenatal Testing and Diagnosis (Part 2) – Dr. Michael Cardwell
The technology of the actual birth hasn’t changed much for many years, but amazing new technology is revolutionizing prenatal diagnosis and testing. For many years amniocentesis was the only testing option for the diagnosis of genetic abnormalities. It is still the gold standard, but new screening methods have dramatically reduced the need to perform an amniocentesis.
We used to offer amniocentesis to women over 35 as a first line test. The procedure does carry some risk of pregnancy loss. The First Trimester Screen, which is a combination of a measurement of several pregnancy-produced proteins in Mom’s blood and a specialized ultrasound, is 96% accurate in detecting the most common chromosomal problems at no risk to the pregnancy. The test can be done as early as 12 weeks.
An even newer test is able to detect fetal DNA in Mom’s circulation (more proof that Mom’s do have special insights and intuition about their kids) as early as 10 weeks of pregnancy. This test is 99% accurate. It tests for the most common chromosomal abnormalities. It also tests for the sex chromosomes, although it is not used just for that reason.
It is now possible to screen for genetic abnormalities prior to pregnancy. We all carry our own individual, distinctive DNA. Each of us has many gene mutations or mistakes. Since we each have two sets of chromosomes the mutations aren’t usually an issue for us. They can be an issue in our offspring, depending on the particular mutations that our partner carries. It is possible now to test a couple to see whether they are at risk of passing two bad copies of a gene to their child. Hundreds of genetic conditions can be tested for with these tests. For couples with known increased risk, these tests are a great options. The cost of the testing has become very reasonable so that even couples without any known risk can opt for the security of the test.