Genetic Testing During Pregnancy: What You Should Know

It was not so long ago that becoming pregnant and having a baby was a lot less monitored, a lot less invasive, and a lot more passive. Up until fairly recently, women became pregnant and spent the next nine months simply waiting to find out the gender of their baby. Today, that waiting seems largely antediluvian—expectant couples can find out pretty much immediately if they are having a girl or a boy. Well, not immediately, but as early as 10–11 weeks into the pregnancy, which is, relative to nine months, almost immediate.

So, overall, genetic technologies and diagnostic tests to check for genetic disorders and are changing the way women have kids as well as the kids that they have. Every aspect of pregnancy is now seemingly in a test tube and this is true even before the pregnancy begins—even before fertilization when sperm meets the egg. More and more pregnant women and their partners are analyzing whether they are disease carries and could possibly pass on their genetic mutations to their offspring. Furthermore, the testing does not stop once a woman does become pregnant. The first trimester is all about testing for chromosomal abnormalities as well as potential deletions or insertions/duplications that may or may not point to potential genetic abnormalities of the baby.

This potentially renders parents-to-be more anxious, as receiving potentially unexpected results about a potentially unhealthy baby can cause upheaval. However, looking at it from another perspective, parents can begin seeking out support groups as well as networks long before the baby is born and as such can ensure that they receive all the care they need. This puts them in the driver’s seat, so to say, which can have many benefits for the future well-being of the baby.

Parents can also find out about disorders such as Down Syndrome, which could be motivation to switch the care they are receiving to more specialized hospitals as well as physicians. So, overall, there are several benefits to genetic screening during pregnancy, despite the fact that they may be nerve-wracking. Before we get into some of them, it is important to differentiate here genetic testing from genetic screening. While the former is more specific as it helps you figure out if a baby actually does have a condition or not. The latter, on the other hand, is a helpful way to figure out if a pregnancy has a predetermined higher risk for genetic conditions based on the parents’ health profile. With genetic screening, parents ought to be reminded that it is not a sure way to know if their baby will have a disease or not—it is simply a prognostication based on the parent’s health backgrounds.

recommended for pregnant women

So, what are some of the genetic tests that are available as well as recommended for pregnant women? During the first trimester, the options are genetic carrier screening that can point out if one or both of the parents are “carriers” of a gene that can be passed on to the kids. Also during the first trimester, mothers can undergo a nuchal translucency ultrasound that measures the tissue at the back of the baby’s neck. While the ultrasound is not a genetic test per se, it can point out potential birth defects such as heart problems. If the ultrasound test comes back as positive, further genetic testing is suggested. Furthermore, another test that is available is Non-Invasive Prenatal Screening (NIPT) that looks for potential abnormalities in the baby’s DNA through the mother’s blood. Detectable genetic abnormalities are associated with Down Syndrome, Trisomy 13, Trisomy 18, and Triploidy as well as Turner syndrome. Some NIPT tests also have the ability to pick up on microdeletion (small missing pieces of a gene) syndromes. This test also has the capacity to inform the parents if they are having a boy or a girl. Chorionic Villus Sampling (CVS) is also available during the first trimester. This test is based on a sample of the fluid that surrounds the sac that contains the baby (the placenta) and it can diagnose both genetic birth defects as well as other genetic conditions. It is the most invasive of all of the genetic pregnancy tests as it involves a large needle that is inserted through the abdomen in order to obtain the sample for genetic testing. Another invasive genetic test is amniocentesis that is performed similarly to CVS, namely a sample is extracted from the placenta for the purposes of genetic testing. As both the CVS as well as amniocentesis are invasive, they do come with a small risk and can cause a miscarriage. However, the frequency is an approximate one out of every 100 pregnancies (or 1%) that are terminated as a result of the tests’ invasiveness.

In terms of genetic testing during the second semester, it is pretty similar to tests that are available during the first trimester. In case that the first-trimester window is missed, tests that are available during the second trimester include tests that are called ‘triple’ and ‘quadruple’ tests. Overall, they look for the same genetic abnormalities as the tests during the first trimester based on amounts of alpha-fetoprotein, human chorionic gonadotropin,and estriol—and inhibin A in the quadruple scenario—in order estimate the risk of a fetus developing a potential genetic defect. However, these tests are only telling of the risk for defects rather than telling for sure that there is a problem. In case of positive results, doctors point to further confirmation testing.

Of course, the time difference should be taken into account, in case of unexpected results. The later on in the pregnancy the parents find out about potential risks, the smaller the window becomes if they do choose to terminate it.

Overall, having the chance to find out about the health of the baby is a health benefit that can keep parents informed and at ease. It can also prepare future parents for what to expect so that they can make the best as well as most informed decisions.

Laura Day
 

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