Medical advances -- such as genetic testing applied to reproductive medicine -- offer helpful new techniques designed to improve your chances of having a healthy baby.
If in vitro fertilization (IVF) is used - where embryos are created by combining eggs and sperm in the lab - preimplantation genetic testing (PGT) can check for abnormal chromosomes or genes so that genetically unhealthy embryos are not transferred to the uterus, improving the likelihood of a healthy live birth.
All women at all ages have some eggs with chromosomal and genetic abnormalities and this increases with age. Some women may also have a medical history and other factors that increase their risk of specific chromosome or genetic abnormalities. This all reduces the chances of making an embryo that will enable a woman to get or stay pregnant with a healthy baby.
To address these issues, couples may choose to have one of two types of genetic testing - preimplantation genetic diagnosis (PGD) to determine whether their embryos have a chromosome or genetic problem for which they are known to be at higher risk, or preimplantation genetic screening (PGS) for those women who don't have a known pre-existing higher risk of genetically abnormal embryos.
Testing to identify abnormalities is done on cells from the embryos created through IVF and now is almost always done on day 5 or 6 blastocysts using different techniques. Techniques include fluorescent in situ hybridization (FISH) and single-nucleotide polymorphism (SNP).
Newer approaches commonly used include array comparative genomic hybridization (aCGH) and next generation sequencing (NGS) and real-time PCR (RT-qPCR). This type of testing is constantly evolving to deliver more information with better accuracy.
PGD tests embryos for genes that may produce a specific disease such as cystic fibrosis, muscular dystrophy, sickle cell anemia or hemophilia. And, every year more tests are available to check for diseases which have a genetic component. In fact, PGD is often used by couples who don't have fertility issues but carry a risk of passing on genetic disorders.
This test can determine if the embryo does or does not have the gene associated with the specific disease. Or, the test may reveal the embryo does carry the gene but a child would be unaffected by the disease. Generally, only one screened blastocyst should be replaced in women even up to their early 40s.
PGS involves checking embryos to make sure the number of chromosomes is normal. Newer tests can also identify some gene abnormalities, but we still don't know the impact of some of these abnormalities on the health of the person resulting from the embryo. Abnormalities can be associated with the ability of the embryo to implant in the uterus, potentially resulting in failure of early embryonic development and miscarriage, later pregnancy complications or birth of an abnormal baby.
PGS is most often suggested for older parents-to-be, someone with multiple miscarriages, or those who have tried multiple fertility treatments without success. When the test was first developed, it was primarily used for women over the age of 38. Infertility specialists expected pregnancy rates to rise by eliminating embryos with abnormalities but this has not been proven to happen. As a result, research is ongoing to improve the accuracy and understanding of this type of screening through large controlled clinical studies that can help us learn better who would benefit by using PGS.
Still, emerging clinical data is encouraging and fertility clinics are expanding the patient population for which they recommend PGS. Until more studies are completed, exactly which patients will definitively benefit is unclear and debate will likely continue until we have more and better research studies.
Whether or not you should have your embryos undergo genetic testing before implantation depends on your individual situation. Infertility treatment is intensely personal and can be complex, so discussing options with your fertility specialist can help you make the best decisions to increase your chance of having at least one healthy baby, and possibly more if you want.
For more information on fertility visit us at ARCFertility.com.