Miscarriages & IVF Implantation Failures—Is PGT-A a Solution?
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Why Do Miscarriages or Abortions Happen?
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What is Chromosome Abnormality?
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Likelihood of having chromosomally normal embryos
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How PGT-A can Help Identify Embryos at Higher risk of Miscarrying?
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PGT-A Recommendations for Miscarriages & Embryo Implantation Failures
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Want to know more about PGT-A?
Miscarriages/abortions are a constant worry in all pregnancies, not just those achieved through IVF but also natural ones. For many women, the miscarriage word lays heavy, bringing, and a flood of emotions that is all-encompassing: shock, sorrow, guilt, confusion. If you haven’t yet experienced a miscarriage, then it is a good opportunity to know about why miscarriages happen and what factors contribute to miscarriages?
1 in 4 pregnancies ending in a loss. Infertile patients who use ART (Assisted Reproductive Technology) procedures are especially afraid of the miscarriage possibility! Often their fertility journey has already involved much loss. What could be done to minimize the risk? If you suffer from recurrent miscarriages, what are your options?
To know answers to all the above queries and more about PGT-A, let’s get into detail:
However, over the last 15 years, along with various reproductive techniques, a new technology called PGS Preimplantation Genetic Screening or PGT-A Preimplantation Genetic Testing for Aneuploidy has been shown to help minimize the likelihood of miscarriages. In people who are pursuing IVF (In Vitro Fertilization), PGT-A may bring new hope to those trying to get pregnant after loss and also for the couples who might be just beginning their journey to parenthood.
While no method of ART Assisted Reproductive Technology (ART), including IVF procedure or genetic testing, guarantees to achieve or sustain a successful yet healthy pregnancy. As per the studies data collected from the tested samples depicting that the addition of genetic screening methods like PGT-A in an IVF cycle can reduce the risk of miscarriage.
Why Do Miscarriages or Abortions Happen?
Miscarriage or spontaneous abortion is defined as the natural loss/death of an embryo or fetus before 20 weeks of pregnancy. it occurs in 30% of all natural conceptions and 10% of all clinical pregnancies. The term recurrent miscarriage means the premature ending of at least two consecutive pregnancies and this affects about 1-3% of all women.
Various Factors contribute to pregnancy loss and some patients also experience an early miscarriage. Here are some myriad of reasons that can cause miscarriage, such as:
- Uterine anomalies
- Infectious causes
- Endocrine reasons
- Immunologic reasons
- Genetic reasons like embryo aneuploidy
- Thrombophilia
- Decreased endometrial receptivity due to uterine abnormalities
Approximately, 80% of pregnancy losses occur in the 1st trimester (before 13 weeks of pregnancy). There are various reasons for pregnancy loss, and in some cases, the specific reason is not identified. And most of all, 50% of first trimester miscarriages are the result of chromosomal abnormality in the developing baby.
What is Chromosome Abnormality?
Let’s get back to school biology. Chromosomes are the structures that carry genetic material, they contain the instructions for appropriate growth & development, each cell of the body contains 46 chromosomes and are inherited in pairs. Each pair of chromosomes are in each copy of one pair comes from the egg and another copy of the pair comes from the sperm. They combine and create the embryo and that further develops into a baby.
The 1st 22 pairs of chromosomes are also known as autosomes and they are the same in males and females. Where the 23rd pair is the sex chromosomes. Individuals with a pair of X chromosomes are chromosomally female, whereas individuals with one X & one Y chromosome are chromosomally male.
Anytime an embryo is formed, whether in a natural pregnancy or as a part of an IVF cycle, there is a risk that an embryo may have an incorrect number of chromosomes, this may be due to few chromosomes (Monosomy), too many chromosomes (referred as trisomy or any missing or extra pieces of chromosomes referred to as trisomy or partial monosomy.
Most chromosomal issues are not inherited and they occur by chance alone. Significantly the risk of successfully implanting an embryo with a chromosome issue increases as women age, but regardless of the age of the woman or as egg or egg donor.
If an embryo is formed with an incorrect number of chromosomes, implants & pregnancy begins, and in most cases, the conception will end in a miscarriage.
Likelihood of having chromosomally normal embryos
Once the eggs are retrieved from the donor, we could reasonably expect around 61% of the embryos are normal and when women are 35 or younger, around half of the embryos will be euploid. Once women cross that age limit, there is a significant decrease in the number of healthy embryos. This could become more severe even after the age of 40 when women age is over 42 and less than 11% of embryos might be chromosomally healthy.
How PGT-A can Help Identify Embryos at Higher risk of Miscarrying?
The PGT-A process is simple, the patient undergoes controlled ovarian stimulation, as usual, the eggs are retrieved and fertilized with the male partner’s sperm using the ICSI procedure, after which the newly formed embryos are allowed to develop for 5 days.
For patients who are completing the IVF cycle, it is possible to screen embryos for chromosomal abnormalities before transfer using PGT-A technology. For this evaluation, on the 5th day, the biopsy (a small sample of cells) is taken from the outer layer of the embryo. And those cells are then analyzed to find out the apparent number of chromosomes present.
The PGT-A testing identifies whole chromosome losses, whole chromosome gains, and losses and gains of large pieces of chromosomes. In most cases, PGT-A provides one of the three following results:
- Euploid—An embryo sample that has the correct number of chromosomes is identified as the “euploid”.
- Aneuploid—The embryo sample having the incorrect number of chromosomes that is identified as “aneuploid”.
- Mosaic embryo sample—meaning some of the tested cells have the correct number of chromosomes whereas others had an incorrect number of chromosomes. Mosaic results might be difficult to interpret as well as decide to transfer these embryos might be quite challenging.
Whatever the result might be, MotherToBe’s genetic counseling team is always available to help understand patients’ PGT-A results.
Many PGT-A test results are typically greater than 97% accurate and mainly they are actionable. After reviewing PGT-A test results with the embryologist /fertility specialist, you two may work together to prioritize the most viable embryos for transfer to embrace successful yet healthy conception results.
PGT-A Recommendations for Miscarriages & Embryo Implantation Failures
PGT-A is one of the recommended diagnostic procedures for infertile and sterile patients, and those who have genetic or hereditary diseases with chromosomal abnormalities. It is also proposed to people whose maternal age is over 38, whose sperm quality is poor, as well as those who have had several IVF failures and others.
Other candidates for PGT-A are women who have had recurrent pregnancy losses, around 60-80% of miscarriages are caused due to chromosomal abnormalities, which is the key factor to propose PGT-A. The simple act of making sure that the transferred embryo is chromosomally correct and healthy provides a significant decrease in pregnancy loss.
Want to know more about PGT-A?
The impact of a miscarriage is significant, the emotional toll due to one or more pregnancy losses may have on a woman or a couple is profound. As there are several options available that might be able to lower your risk of miscarriage, including genetic screening options before as well as during pregnancy.
PGT-A, despite being an invasive procedure that requires extreme precision, MotherToBe’s embryologist are highly trained and experienced to provide precise genetic information about embryos while also helping to improve conception rate and decrease miscarriage rates.
We wish you the best on your journey to parenthood!