It is indeed important to establish the genetic health of an unborn baby. Any pregnancy will in fact be closely monitored by specialists to ensure the health development of the child. Monitoring is done via either screening tests or diagnostic tests.
There are several types of screening tests. Although some of these tests can indicate that the unborn child may be affected by the disease they cannot confirm whether the child is actually suffering from the diseases. With regards to this latter issue, there is no test available than can tell a pregnant woman with 100% accuracy whether the baby will be born with a genetic disease.
Ultrasounds work by emitting sound waves and can be used to determine a number of chromosomal abnormalities. An ultrasound can, for example, strongly indicate the possibility of Down syndrome by what is termed “fetal nuchal translucency”. Thus, what the person overseeing the ultrasound does is closely observe the folds and creases on the neck of the fetus. Babies with Down syndrome will often have a larger neck due to the accumulation of a certain fluid in this region of the body and thus, this becomes a telling feature of Down’s. Ultrasonography can also indicate other autoimmune conditions such as Turner’s syndrome, Edward’s syndrome and Patua’s syndrome.
Maternal Serum testing
Maternal serum testing is another type of screening prenatal test and is done via the analysis of maternal blood. This test measures an enzyme, alpha-fetoprotein, which is only produced by the mother during pregnancy. Maternal serums tests can indicate Neural tube defects such as Spina Bifida as well as Down’s syndrome.
If screening tests strongly suggest the presence of chromosomal abnormalities, the OBGYN may suggest going ahead with some diagnostic tests which can provide a more definite answer.
Because autoimmune diseases are hereditary, expectant mother may be encouraged to undergo early screening tests if they have any of the conditions. Down syndrome is not however, considered a hereditary illness, unlike for example, sickle cell anemia.
Diagnostic Testing for your Baby’s Genetic Health
If screening tests indicate the possibility of a autoimmune or hereditary disease then diagnostic tests can enable a better assessment by actually analysis the baby’s genetic makeup. To be able to analyze the baby’s genetic makeup however, scientists needs to have access to the fetus’s DNA. There are two main methods which can be used.
Chorionic villus sampling is a method by which samples of finger-like protrusions known as chorionic villi are collected from the uterine wall. This test can be done at around 11 weeks of pregnancy and requires assistance of an OBGYN. Samples can be collected in two ways:
- Transabdominal sampling: in this case a needle is inserted through the abdomen and into the lining of the womb known as the placenta.
- Transcervical sampling: in this case a catheter is inserted through the cervix and into the womb.
Amniocentesis is another method for fetal DNA sampling which can be carried out at around 14 weeks. The test involves insertion of a needle into the womb and the extraction of a small amount of amniotic fluid.
Both these two above tests are far more accurate at diagnosing chromosomal abnormalities such as Spina Bifida or cystic fibrosis than screening tests. It is however, very important to understand that they are not 100% accurate. They do have a 1-2 % margin of error. They moreover, carry certain risks to the unborn fetus including injury to the limbs and miscarriage.
Fetal DNA sequencing from Maternal Blood
Recent advances in the field of DNA testing means that scientists have successfully isolated fetal DNA from samples of peripheral maternal blood. There are a number of companies offering such tests (such easyDNA Ireland , The Genetic Testing Laboratory and International Biosciences) and others still working on developing more accurate ways of determining fetal abnormalities non invasively. This presence of fetal DNA in the blood stream is due to fetal DNA finding its way across the placental barrier into the mother’s blood stream. The amount of fetal DNA will also increase as pregnancy weeks pass. The advantages of this type of sampling is that it is totally non invasive and risk free. This analysis can be used to detect chromosomal abnormalities, baby gender and as well paternity testing in pregnancy. For more information about fetal DNA sampling visit this webpage.