If you’re a fertility patient considering in vitro fertilization (IVF), there can be a lot of uncertainty about your chances of having a baby with IVF. Certainly, Univfy IVF Prediction Tests can help you with that. Once you have your embryos through IVF, pre-implantation genetics can offer one way to reduce uncertainty.
How would that work? As part of your IVF treatment, you will take medications to stimulate production of your eggs. Your doctor will then retrieve the eggs and enable your partner’s sperm to fertilize them in a laboratory dish. Then, the doctor will transfer the fertilized egg, now called an embryo, back into your uterus to start a pregnancy.
Before the doctor implants the embryo into your uterus, you can request pre-implantation genetic testing of your embryos to see if they might have genetic problems that can interfere with a normal pregnancy and healthy delivery. Pre-implantation genetic testing is only possible with embryos that are a result of IVF.
Two major types of pre-implantation genetic testing are available to you: Pre-implantation genetic screening (PGS) and pre-implantation genetic diagnosis (PGD). The two, often confused with each other, are actually used for different purposes. But both can help doctors and their patients decide which embryos are genetically normal and the best to transfer for the greatest chances of a full-term pregnancy and a healthy child.
First, a little background on what doctors are looking for with PGS or PGD: Some percentage of embryos, no matter what, will always have an abnormal number of chromosomes in their cells. Our cells have 23 pairs of chromosomes for a total of 46 chromosomes. At conception, we get 23 chromosomes from our mother, and 23 chromosomes from our father, including 22 gender-neutral chromosomes (the same whether you’re female or male). In addition, we have two sex chromosomes (the X and Y chromosomes), which determine whether we will be male (XY) or female (XX).
As women age, they’re more likely to have eggs that have an chromosomal abnormality, because the ageing genetic machinery is less effective at correcting problems that arise as the egg matures. Embryos with chromosomal abnormalities, a condition called aneuploidy, usually die before implantation in the uterus, or early in pregnancy, causing a miscarriage.
Just so you know, a few chromosomal abnormalities do not result in pregnancy failure or early pregnancy loss, so we have children and adults with chromosomal abnormalities. The most common is an extra Chromosome 21, a genetic condition called Trisomy 21, the cause of Down syndrome.
PGS identifies embryos with the correct number of chromosomes to help choose which embryos (usually one, or sometimes two) are transferred to the uterus. Patients with recurrent miscarriage or a known tendency to have embryos with abnormal chromosomes may benefit from PGS.
PGD, on the other hand, checks whether a patient’s embryos have a very specific genetic variation that is known to cause debilitating or fatal medical conditions that run in the family. PGD testing looks for abnormal gene sequences within the chromosomes in the embryo that will lead to health problems for the child or in subsequent generations.
Should every IVF patient use pre-implantation genetic testing? Testing can bring huge benefits for some, increasing the chances of a healthy pregnancy and avoiding the risk of passing on deadly genetic diseases. For others, the benefit may not be worth the extra expense and possible risks. The technique to remove cells for testing (called embryo biopsy) carries an extremely small risk of damage to the embryo when performed by a highly skilled technician. And at any rate, doctors still recommend prenatal testing for genetic abnormalities using traditional tests, such as chorionic villus sampling and amniocentesis, to confirm pre-implantation genetic test results. As PGS becomes more widely available (and in demand), we will learn more about the impact of PGS on increasing live birth rates or reducing miscarriage rates with older women, women with repeated failed IVF cycles, and those with recurring miscarriages.
Be sure to talk with your doctor or a genetic counselor to help you decide if you want to pursue pre-implantation genetic testing.
To learn more, click here to read Univfy guest blogger Dr. Ronald Feinberg's informative blog post on The ABCs of PGS.