What is first trimester screening?
First trimester screening is a test that is performed between about 11 -14 weeks. It is a screening test for some of the more common chromosomal problems such as Down Syndrome. The test is 2 parts, an ultrasound that is looking at various “markers” that are more common in babies with abnormalities. This alone will identify about half of the babies at risk for chromosomal issues. The 2nd part is adding blood work from the mom which can increase this detection rate to approximately 80%. Approximately 5% of the time, the test will return as “positive” or concerning for Down syndrome but it does not mean the baby will have Down syndrome. It raises a “red flag” that the risk is now increased to the point that we should have you meet with one of our genetic counselors to discuss more definitive testing options. Most women who come back high risk for Down syndrome with first trimester screening will not have a baby with this condition; most high risk results are false positives.
What do I do if the first trimester test is positive?
You will generally meet with one of our experienced genetic counselors who will discuss additional testing options. This could involve more blood work from the mom or a diagnostic test where a sample of the placenta or amniotic fluid is obtained. The blood work is called cell free DNA (NIPS or NIPT) which is a relatively new test and is very accurate for Down syndrome and involves no risk to the pregnancy. A diagnostic test does involve a small risk of miscarriage but is much more accurate, especially for other chromosome abnormalities. The specifics of each of these will be reviewed in much more detail with the counselor if the need were to arise.
What is this “gender test” I have heard so much about?
Cell free DNA is a blood draw that is designed to screen for certain genetic conditions. An optional portion of the test can included predicted sex of the baby. All people have some DNA, which are part of our genetic instructions, free floating in our blood. In pregnant mom’s, about 10% of the DNA in her blood comes from the placenta which can be used to screen for Down syndrome, trisomy 18, and trisomy 13. While this test has higher accuracy compared to first trimester screening, it is not diagnostic and it still does not provide "yes" or "no" answers.
Some families might consider cfDNA as an option to learn sex of the baby earlier in pregnancy. It is important to remember that while finding out sex of the baby is fun and exciting, this test's purpose is to screen for genetic conditions and we sometimes find out the baby is high risk for a certain condition.
Additionally, not all insurance will cover cfDNA and this test can expensive even with insurance coverage. We recommend contacting Ariosa directly to help learn the costs might be if you are interested in testing.
If you are interested in a blood draw test that only includes sex of the baby we recommend looking online for options that don't require a doctor to order. These other options can also be cheaper for families compared to cfDNA screening.
Do I have to have any genetic testing?
No one is forced to have any genetic testing. The goal of genetic counseling is to allow parents the choice to gain more information about the health of their baby if they desire. Having additional knowledge regarding their baby’s health can assist parents in making more informed decisions by researching specific disorders, discussing the situation with experts, reaching out to families who had a similar situation, identifing support groups, or consulting with clergy. This knowledge can help guide management of a pregnancy, allow for the optimal timing of delivery, along with possibly needing to delivery the baby at a facility with extensive pediatric support so the baby gets the expert attention it needs immediately. This carefully orchestrated delivery with all the necessary people available can help in obtaining the best outcome possible. Having “surprises” in the delivery can result in more complications for the baby than necessary and result in an emergent transfer to a hospital with an intensive care nursery. This could result in the separation of mother and baby which we strive to avoid at all costs.