For almost all of human history, we didn’t know anything about a baby until it was born — but we’ve always wanted to. Every culture seems to have its own age-old method for guessing the gender of a baby, but that’s all we had until the advent of amniocentesis and chorionic villus sampling (CVS). These effective albeit invasive tests for detecting genetic abnormalities in the fetus came about only in the latter half of the twentieth century.
In the past decade, non-invasive prenatal testing (NIPT) made a grand entry into pregnancy. Instead of using a needle to extract fetal DNA from the uterus in the second trimester of pregnancy, NIPT uses cell-free DNA from the fetus found in the mother’s blood to detect the risk that the child may have a genetic abnormality like trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), or trisomy 13 (Patau syndrome) in the first trimester. The scientific community has come a long way in developing prenatal screening tests that eliminate the risk to the fetus and can be performed early in the pregnancy. What’s next in the field of prenatal testing?
1. Earlier and More Definitive Testing
Right now, NIPT is offered as an option to all pregnant women as early as week 9 of pregnancy. This is toward the end of the first trimester, around the 25% mark of the 40 weeks of gestation. Because NIPT is a screening test that is not yet definitive, receiving a positive result only leads to a referral for further, definitive testing with amniocentesis or CVS, as late as the middle of the second trimester.
Scientists are striving to change this. The expectation is that soon, through the development of blood tests that can detect abnormalities earlier and more definitively, medicine will be able to inform parents about genetic disorders earlier. This will allow families more time to seek genetic counseling to understand their results and plan for their child to receive the very best care and resources for healthy development.
2. Testing that Detects More Disorders
While NIPT has revolutionized prenatal care, it is still limited in terms of the genetic abnormalities it can detect. Scientists have not yet determined how to fully separate fetal DNA from maternal DNA in the mother’s bloodstream, so NIPT is able to pick up on things that are relatively “easy” to find. For example, the presence of a whole extra chromosome in the DNA is easier than detecting mutations in specific genes. Figuring out how to do this is a major focus in prenatal genetics today.
3. Therapies that Correct Genetic Abnormalities
Ultimately, the goal is to learn not only to detect, but to correct genetic abnormalities. This can potentially be accomplished either before implanting the embryo in the case of IVF, or even in utero in the case of natural conception. In the initial stages, scientists may aim to develop therapies to lessen the effects of genetic abnormalities. Though we’re not there yet, eventually, the task at hand is to learn to help babies who develop an abnormality at conception or in the embryonic stage to be born healthy.
SOURCES:
1. https://www.babygaga.com/12-weird-ways-different-cultures-predict-the-babies-gender/
2. https://embryo.asu.edu/pages/chorionic-villus-sampling
3. https://embryo.asu.edu/pages/amniocentesis
4. http://time.com/expectingbetter/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4470183/
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