Written by Guest Expert Dr. Harvey Stern, MD, PhD, FACMG, FAAP
Genetic testing is now an established component of all pregnancies, including those utilizing surrogacy. The scope of genetic testing currently includes preconception, preimplantation, prenatal, and postnatal genetic testing. Unless one is familiar with genetics, navigating genetic testing can be very intimidating. You may feel overwhelmed by the decisions you need to make and unsure of where to turn for support.
In this post, we will provide guidance on how to approach genetic testing, including tips on how to choose the right tests among the available options, how to communicate with your surrogate, and where to find additional resources.
Genetic Disease Carrier Screening
All intended parents, whether considering surrogacy, assisted reproduction, or natural conception, should consider being screened for carrier status of heritable genetic disorders in the reproducing partners.
There are 22,000 genes in the human genome. Many of these conditions are inherited as recessive disorders. An autosomal recessive disorder means two copies of an abnormal gene must be present (one from each parent) in order for the disease or trait to develop. The parents, who are called “carriers,” have one normal and one abnormal gene but have no clinical symptoms due to the presence of the one normal gene. Abnormal recessive genes, therefore, can “run in families” for many generations without anyone knowing about it (unless you test). Examples of these conditions are Cystic Fibrosis, Tay-Sachs disease, and Sickle Cell disease.
There are several different panels of genes that are commercially available and can be used to test parents for carrier status. Some are basic and involve only three common conditions, and others offer more expanded genetic disease carrier testing of over 500 different genes. Interestingly, the cost of testing is usually similar regardless of the number of genes in the panel. Since cost is not a factor, we typically recommend screening using a large panel to obtain the most information. The best time to do carrier screening is before becoming pregnant as this offers the most options for going forward in the pregnancy, including preimplantation genetic testing if necessary.
Prenatal Diagnosis vs. Preimplantation Genetic Testing
Prenatal diagnosis and preimplantation genetic testing (PGT) are two different approaches used to identify genetic disorders in embryos or fetuses.
Prenatal diagnosis involves testing of an ongoing pregnancy (usually a single fetus) in the uterus at 11 to 23 weeks gestational age. This can be done through various methods, such as chorionic villus sampling (CVS) or amniocentesis. Abnormalities such as having an extra or too few chromosomes or gaining or losing specific pieces of a chromosome can be directly identified. For embryos, this is called PGT-A (aneuploidy). Detection of single gene defects (PGT-M monogenetic disorder) requires previous identification of the specific, disease-causing change in the DNA in a previously affected child or other family member.
While prenatal diagnosis involves testing the fetus during pregnancy to determine if there are any genetic abnormalities or congenital disorders, preimplantation genetic testing (PGT) is a technique that is used before implantation to test embryos created through in vitro fertilization (IVF) for specific genetic abnormalities. PGT involves removing 5-8 cells from the embryo on the 5th to 7th day after conception and testing them for specific genetic mutations or chromosomal abnormalities. The embryos found to be free of genetic disorders are then available to be implanted in the uterus of the patient or surrogate.
What are the different types of preimplantation and prenatal genetic tests?
There are several types of tests that can be done on embryos to check for genetic disorders or other conditions, including PGT-A (preimplantation genetic testing for aneuploidy (chromosome abnormalities), PGT-M (preimplantation genetic testing for monogenic/single gene defects) and PGT-S (preimplantation genetic testing for patients with structural chromosome rearrangements).
- PGT-A tests embryos for extra or missing chromosomes, which can cause serious health conditions like Down syndrome and other chromosomal abnormalities. It is frequently done in conjunction with IVF before the embryo is transferred into the surrogate’s uterus.
- PGT-M looks at a single gene mutation that may be associated with a specific disorder. It is used to identify embryos that do not carry specific genetic mutations that cause certain diseases or medical conditions.
- PGT-S is used to identify structural abnormalities in the chromosomes. These can cause serious medical problems and even lead to miscarriages. It is typically done after IVF when cells from the embryos are taken for analysis.
In addition to the preimplantation tests, it is also possible to do genetic tests during pregnancy. Non-invasive tests such as First Trimester Screening (FTS) and Non-invasive prenatal testing (NIPT) are screening tests that do not provide a definitive diagnosis but are capable of further defining the patient’s risk of carrying an abnormal pregnancy. Those at high risk can then seek a definitive diagnosis by CVS or amniocentesis.
- First Trimester Combined Screening is a screening test that combines a blood test, a specialized ultrasound, and maternal information such as a woman’s age. It estimates the chances for two common chromosome abnormalities in pregnancies: trisomy 21 (Down syndrome) and trisomy 18 (Edwards syndrome). Each of these conditions can occur in any pregnancy, and they cause both physical and developmental abnormalities. FTS also offers an opportunity to view the fetus to screen for certain birth defects, and it may identify pregnancies at increased risk for other chromosome disorders, placental complications, or other obstetrical risk factors.
- Non-invasive prenatal testing (NIPT) is a blood test done during the late first trimester that can identify Down syndrome, trisomy 18 and 13, and a few other genetic conditions. The test is a screening test and involves taking a sample of maternal blood and looking at cell-free DNA present in the maternal plasma. This is of fetal origin and can therefore be used to evaluate for chromosome disorders.
- Chorionic villus sampling (CVS) is a procedure to remove a small amount of tissue (called chorionic villi) that will later become part of the placenta. This tissue is within the uterus but outside of the gestational sac where the fetus is located. The tissue provides information about the chromosome or other genetic disease status of the developing fetus. CVS is performed either by guiding a thin needle through the woman’s lower abdomen into the uterus or by guiding a thin, flexible catheter through the cervical opening after inserting a speculum in the vagina. Ultrasound is used for guidance, and the location of the placenta on the day of the procedure will determine which approach is used.
- Amniocentesis is a procedure to remove a small among of amniotic fluid from the uterus. The fluid contains cells that have been shed by the fetus. The sample is used for chromosome or other specific genetic tests and to screen for open neural tube defects.
Each of these tests can provide different information about the health of the fetus. The specific tests recommended will depend on the couple’s medical history, age, and other factors.
How do I choose the right tests?
Genetic testing is an important part of the IVF process for intended parents and surrogates alike, but when it comes to choosing the right prenatal genetic tests, the decision can be overwhelming.
Choosing the right prenatal genetic tests can be a complex process that requires careful consideration of your individual situation, medical history, and personal preferences.
Some factors to consider include:
- Medical history: Your personal and family medical history can provide important information about your risk of having a child with a genetic disorder. If you or your partner has a family history of a specific genetic condition, your doctor may recommend genetic testing to screen for that condition.
- Age: Maternal age increases the risk of having a child with a chromosomal abnormality or genetic disorder. Women over 35 years old are generally considered at higher risk and may be recommended for more extensive testing.
- Personal preferences: Some couples may choose to undergo genetic testing even if they are not at high risk of having a child with a genetic disorder, simply for peace of mind. Others may prefer to avoid invasive tests like CVS or amniocentesis due to the small risk of complications.
- Test accuracy: The accuracy of prenatal genetic tests can vary depending on the specific test and the timing of the test. It’s important to talk to your doctor about the accuracy rates of different tests and what kind of results you can expect.
Once you have a clearer idea of what tests you would like to pursue, you can start researching and talking to your doctor about which tests would best suit your needs. When going through surrogacy, communication between intended parents and their surrogate is key when deciding which tests to pursue. Surrogates should feel comfortable participating in the decision-making process and expressing their own opinions and concerns when discussing prenatal testing options.
As an intended parent, it’s important to ensure that any testing decisions involve both parties in order to reach a consensus. Establishing clear lines of communication before any discussions about prenatal testing can help create a smooth dialogue and increase mutual understanding between both parties.
How do I communicate with my surrogate about prenatal testing decisions?
During the matching phase, it is important to understand your options and have an honest conversation with your surrogate about your desires and expectations regarding prenatal testing. You should also ask her if she has any questions or preferences when it comes to prenatal testing during pregnancy.
Communication with your surrogate is key when making decisions about prenatal genetic testing. It is important to ensure that your surrogate understands the implications of the tests, how they will affect her and the child, and how they will impact the overall surrogacy process.
Be clear in explaining the purpose of each test, the potential risks and benefits, and how the results may affect the pregnancy and delivery. Let your surrogate know that her input is valued and that you are willing to discuss any concerns she may have.
Finally, make sure you have a plan in place for sharing the results of the tests with each other. Be sure to provide contact information for support and resources should your surrogate need additional information or assistance.
By taking the time to openly communicate with your surrogate about prenatal genetic testing, you can make informed decisions together that are in the best interests of all involved.
How the results can impact the surrogacy process
Prenatal genetic testing can have a significant impact on the surrogacy process for both intended parents and surrogates. Depending on the results of the tests, certain decisions may need to be made that could alter the course of the pregnancy.
For example, if a genetic disorder is detected in the fetus, the intended parents may need to consider options such as terminating the pregnancy or continuing with the pregnancy and preparing for the potential needs of a child with special needs. These decisions can be incredibly difficult and emotionally taxing for everyone involved.
It’s important for intended parents and surrogates to discuss their thoughts and feelings about prenatal testing before the pregnancy begins. This can help to establish a plan and ensure that everyone is on the same page about testing decisions.
Additionally, the results of prenatal genetic testing may impact the legal agreement between the intended parents and surrogate. For example, if the intended parents decide to terminate the pregnancy due to a genetic disorder, the surrogate may need to consent to the termination.
Ultimately, the results of prenatal genetic testing can profoundly impact the surrogacy journey. It’s important to approach testing decisions thoughtfully and communicate openly and honestly with all parties involved. Finding a qualified surrogacy agency with experience in handling prenatal testing and related issues can also be incredibly helpful in navigating this complex process.
Where can I find support and resources?
Embarking on a surrogacy journey can feel overwhelming, especially when it comes to navigating prenatal genetic testing. Thankfully, there are resources available to help intended parents through the process.
Your fertility clinic and OB/GYN should be able to provide you with information about the various types of tests available, as well as recommendations for which ones may be most appropriate for your situation. They may also be able to connect you with genetic counselors or other medical specialists who can answer your questions and offer guidance.
Additionally, your surrogacy agency can offer emotional support by providing you with counseling or referring you to support groups or a mental health professional who can help you find ways to cope with the feelings that any unexpected results may bring. Your agency can also offer additional support to your surrogate and help navigate any legal or medical concerns that may arise.
Take the first step toward your surrogacy journey!
Navigating prenatal genetic testing can be complex and emotional. But with the right support and resources, intended parents can make informed decisions and feel more confident about their surrogacy journey.
At Fairfax Surrogacy, our team is here to provide you with the support you need to navigate prenatal genetic testing and make informed decisions that are best suited to your unique situation. Contact us today to learn more about our services and how we can help you make the most of your surrogacy journey.
About Dr. Stern:
Dr. Harvey Stern, MD, PhD, FACMG, FAAP, is a distinguished specialist in reproductive genetics and fetal diagnostics. Since joining the Genetics & IVF Institute (GIVF) in 1995, he has served as the director of reproductive genetics, providing key services such as amniocentesis, chorionic villus sampling, first-trimester screening, and ultrasound. Additionally, he is the medical director of Fairfax Cryobank and the preimplantation genetic testing (PGT) program for GIVF, and oversees the GIVF endocrinology laboratory.
Dr. Stern’s credentials include board certifications in pediatrics and medical genetics, with subspecialty board certification in clinical, biochemical, and molecular genetics. He is a founding fellow of the American Board of Medical Genetics and Genomics and an alumnus of Columbia University and the Albert Einstein College of Medicine. His professional affiliations include the American Society for Reproductive Medicine, the American College of Medical Genetics and Genomics, the European Society of Human Reproduction and Embryology, and the International Fetoscopy Society.