PGT-M and PGT-A Genetic Screening Before IVF

Woman in lab running a test
Vesna Andjic/Getty Images

Genetic screening technologies like PGT-M (formerly known as PGD) and PGT-A (formerly known as PGS), when combined with IVF treatment, have made it possible to reduce the risk of passing on devastating genetic diseases, possibly lower the likelihood of recurrent miscarriage, and improve the odds of pregnancy success.

As with all assisted reproductive technologies, it’s important to understand which situations the technology is best used for, the possible risks, the costs, and what to expect during treatment.

While PGT-M and PGT-A are both genetic screening technologies used with IVF, they differ in why and how they are used.

What Does PGT-M Mean?

PGT-M stands for "preimplantation genetic testing for monogenic disorders." PGT-M is used when a specific genetic disease needs to be identified in the embryo. This may be desired to avoid passing on a genetic disease or used to choose a very specific genetic tendency.

Sometimes, both are needed—for example, when a couple wants to conceive a child who can be a match for a stem cell transplant for a sibling but also wants to avoid passing on the gene that causes the disease requiring a stem cell transplant.  

PGT-M does not test a single embryo for all possible genetic disease. For example, if an embryo does not appear to have the gene for cystic fibrosis (CF), that doesn’t tell you whether any other genetic diseases are present. It only gives you the assurance that CF is highly unlikely.

What Does PGT-A Mean?

PGT-A stands for "preimplantation genetic testing for aneuploidy." PGT-A does not look for specific genes, but rather at the overall chromosomal makeup of the embryo.

Embryos can very generally be classified as being euploidy or aneuploidy. In a normal situation, the egg contributes 23 chromosomes and the sperm another 23. Together, they create a healthy embryo with 46 chromosomes. This is called a euploid embryo.

However, if an embryo has an extra chromosome—or is missing a chromosome—it is called aneuploidy. Aneuploidy embryos are more likely to fail to implant or to end in miscarriage. If implantation, pregnancy, and birth take place, aneuploidy embryos may result in a child with mental or physical disabilities.

For example, Down syndrome can occur when there is an extra copy of chromosome 21. PGT-A can identify this before the embryo is transferred to the uterus.

PGT-A can also identify the gender of an embryo. Comprehensive Chromosome Screening (CCS) is one technique of PGT-A that can identify whether an embryo is XX (female) or XY (male). This may be used to avoid a gender-linked genetic disorder or (more rarely) for family balancing.

PGT-M and PGT-A vs. Prenatal Testing

Both PGT-M and PGT-A take place during preimplantation, before the embryo has implanted in the uterus. This is unlike prenatal testing, where implantation has already occurred. Prenatal testing can only be done if a pregnancy has been established.

Chorionic villus sampling (CVS) and amniocentesis provide microarray testing, which is not available on embryos. These tests can identify chromosomal abnormalities in a fetus. When abnormalities are suspected during prenatal testing, the options are to either allow the pregnancy to continue or terminate. This can be a difficult decision to make. 

Those who choose to continue the pregnancy face uncertainty and fear of what’s to come at birth. Besides worry about having a child with lifelong disabilities, they may face an increased risk of stillbirth. Those who decide to terminate the pregnancy face grief, possibly guilt, and the physical pain and recovery of abortion.  

Some people have religious or ethical objections to pregnancy termination but are comfortable with genetic testing before embryo transfer takes place. That said, PGT-M and PGT-A are not guaranteed. Most doctors recommend doing prenatal testing in addition to preimplantation genetic testing, just in case a genetic diagnosis was mistaken or missed.

Reasons to Test for a Specific Genetic Diagnosis With IVF

Here are possible reasons your doctor may recommend PGT (or reasons you may request it).

Inherited Genetic Diseases

This is the most common reason for PGT. Depending on whether a genetic disease is autosomal dominant or recessive, the risk of passing on a genetic disorder to a child may be anywhere between 25% and 50%.

In some cases, a couple may not otherwise need IVF to get pregnant, and may not be facing infertility. Their only reason for pursuing IVF may be for preimplantation genetic testing.

As mentioned above, prenatal testing can also test for genetic diseases, without the added expense, risks, and costs of IVF treatment. But since the only option is pregnancy termination (or continuing the pregnancy) after prenatal testing, this is unacceptable to some couples.

Commonly Tested Genetic Diseases

The following list is from Johns Hopkins Medicine:

  • Cystic fibrosis
  • Duchenne muscular dystrophy
  • Hemophilia A
  • Polycystic kidney disease
  • Sickle cell disease
  • Tay-Sachs disease
  • Thalassemia

Translocation

Some people are born with all 46 chromosomes, but a section of one chromosome breaks off and reattaches to another chromosome. This is called a translocation.

People with a translocation may be otherwise healthy, but their risk of experiencing infertility, having a pregnancy result in miscarriage or stillbirth, or having a child with a chromosomal abnormality is higher than average.

For couples that have a partner with a translocation, PGT can be used to help identify embryos that are more likely to be healthy. 

HLA Matching

Stem-cell transplant is the only cure for certain blood diseases. Finding a match within the family is not always easy. However, PGT-M can be used to choose an embryo that would be a stem-cell match (human leukocyte antigen, or HLA match) and possibly avoid passing on that same genetic disease to a sibling.

If an HLA match embryo can be identified and a healthy birth takes place, the stem cells needed to save the life of the sibling can be collected from the umbilical cord blood at birth. 

Genetic Predisposition for Adult-Onset Disease

Though more controversial, PGD is sometimes used to avoid passing on genetic tendencies that may result in disease later in life. For example, while having a harmful variant of the BRCA1 or BRCA2 gene doesn’t mean a person will develop breast cancer, their risk of this disease will be higher.

PGD can be used to screen embryos for harmful gene variants and select those without the variants for implantation.

The Ethics Committee of the American Society of Reproductive Medicine (ASRM) states: "PGD for adult-onset conditions is ethically justified when the condition is serious and no safe, effective interventions are available. It is ethically allowed for conditions of lesser severity or penetrance."

Reasons for General Genetic Screening With IVF

Here are some common reasons PGT-A may be used with IVF treatment.

Improving the Odds for Success With Elective Single Embryo Transfer

A number of studies have found that preimplantation screening can help improve the odds of pregnancy and reduce the risk of miscarriage when choosing elective single embryo transfer.

With elective single embryo transfer or eSET, your doctor transfers just one healthy-looking embryo during IVF treatment. This is instead of transferring two embryos at once, a technique that increases the odds for success but also carries with it the risk of conceiving multiples. Multiple pregnancies bring risks to the mother's and babies' health.

Without PGT-A, the embryo is traditionally chosen based on how it appears. It’s been found, however, that embryos that don’t look perfect under the microscope can actually still be healthy. And embryos that look healthy may not be as chromosomally normal as they appear. PGT-A takes some of the guesswork out.

Identifying Gender

Usually used when a genetic disease is gender-based, PGT-A can help identify whether an embryo is female or male. This can be a slightly less expensive way than PGT-M of avoiding a genetic disease.

However, PGT-A may also be used to help a couple have a child of a specific gender when they hope to “balance” their family. In other words, they already have a boy and now want a girl or vice versa. This would rarely be done if the couple didn’t require IVF for another reason.

The American College of Obstetricians and Gynecologists (ACOG) is ethically against using PGS for gender selection without a medical reason.

Reducing the Risk of Miscarriage

Miscarriage is common, occurring in up to 25% of pregnancies. Recurrent miscarriage—having three or more losses in a row—is not. PGT-A may be used to help reduce the odds of another miscarriage.

The research on whether or not PGT-A can truly improve pregnancy odds for women with a history of repeated pregnancy loss is unclear. While some studies have shown better odds with PGT-A, others have shown no difference. Talk to your doctor to determine the best option for you.

There may be a lower risk of experiencing miscarriage, but a healthy pregnancy and birth may not come sooner. Currently, the ASRM does not recommend IVF with PGT-A in cases of recurrent miscarriage.

Improving the Odds of IVF Pregnancy Success

Some fertility doctors recommend PGT-A along with IVF to increase the odds of treatment success in cases of severe male factor infertility, couples who have experienced repeated IVF implantation failure, or women of advanced maternal age.

There’s currently little research to show that PGT-A improves IVF treatment success when it’s not specifically indicated. Many studies that have found higher success rates are looking at live birth rates per embryo transfer—and not per cycle.

This will always be higher than per cycle rates, because not every IVF cycle results in embryos to transfer. Research has not yet shown whether there is a true advantage.

How Are Embryos Biopsied?

In order to do any genetic testing, cells from the embryo must be biopsied. The zona pellucida is a protective shell that envelopes the embryo. This protective layer must be broken in order to biopsy some cells. To breakthrough, an embryologist may use a laser, acid, or glass needle.

Once a tiny opening has been made, the cells to be tested are removed either with suction through a pipette, or the embryo is gently squeezed until a few cells come out through the broken opening. 

Biopsy of the embryo may be done three days after fertilization or five days. There are pros and cons to each.

Day 3 Embryo Biopsy: An embryo on Day 3 is known as a blastomere. It has only six to nine cells. It’s possible to do genetic screening on just one cell, but taking two is better.

One of the biggest advantages of doing a Day 3 biopsy is that testing can be done in time for a fresh embryo transfer on Day 5 after egg retrieval. This means less wait time and lower cost (since you may not need to pay for a frozen embryo transfer.)

However, some research has found that biopsy of more than one cell at this stage increases the risk of “embryo arrest.” The embryo may stop developing and can no longer be transferred. This is rare, but still a risk to consider. Also, the risk of false positives and inclusive results are greater with Day 3 biopsy.

Day 5 Embryo Biopsy: A Day 5 Embryo is called a blastocyst. At this stage, the embryo has hundreds of cells. Some of these cells will become the fetus, others the placenta. The embryologist can take more cells for testing—usually taking between 5 and 8 cells—which can allow for better diagnosis and fewer inconclusive results.

The cells taken are ones destined to become placenta; the fetal cells are left untouched. A disadvantage of the Day 5 biopsy is that not all embryos survive in the lab environment for so many days, even otherwise healthy embryos.

Also, Day 5 biopsy requires the embryos to be cryopreserved until the results return. This means the woman will need to wait until at least the next month to do the embryo transfer. It will be a frozen embryo transfer cycle, resulting in additional waiting time and additional costs. There is also a risk that the embryos won’t survive the freeze and thaw.

However, only the strongest embryos tend to remain after this process. Those that survive and have good results are even more likely to lead to a healthy outcome. 

What Is the Process for IVF With PGT-M and PGT-A?

There are some differences in how IVF treatment cycles are conducted for PGT-M or PGT-A testing.

With PGT-M, the process may begin months before the actual IVF treatment. Depending on the specific genetic diagnosis needed, genetic testing of family members may be required. This is needed to create a gene probe, which is like a map used to pinpoint exactly where the genetic abnormality or marker is.

PGT-A does not require genetic testing of family members and only involves testing embryos. During the actual IVF cycle, the patient experience of each type of testing are similar, even though the genetic technology in the lab differs.

Where IVF with genetic screening differs from conventional treatment is at the embryo stage. Usually, after the fertilization, any healthy embryos are considered for transfer three or five days after the egg retrieval. With PGT-M or PGT-A, the embryos are biopsied on Day 3 (after egg retrieval) or Day 5. The cells are then sent for testing. If the embryos are tested on Day 3, the results may get back before Day 5. If so, any embryos with good results can be considered for transfer. Extra embryos can be cryopreserved for another cycle.

However, Day 5 biopsy may be recommended or preferred. In this case, the embryos are biopsied and then immediately cryopreserved. No embryos will be transferred during the IVF cycle in this case. Instead, they will remain “on ice” until results from the genetic testing come back.

Once results are available, assuming any embryos are considered transferable, the parent will take medications to suppress ovulation and prepare the uterus for implantation. At the right time, one or a few embryos will be thawed and readied for transfer. 

When a Day 5 biopsy and frozen embryo transfer cycle is chosen, treatment time may span two to four months (with a possible month rest/waiting period.)

Risks of PGT-M and PGT-A

IVF with preimplantation genetic testing comes with all the risks of conventional IVF treatment.

In addition to those, anyone considering PGT-M/PGT-A needs to also understand these additional risks:

  • Live birth rates may be lower than those of age-matched peers. This is because some embryos won’t survive the process and some (or all) may come back with poor results.
  • With Day 5 biopsy, there's a slightly increased risk of identical twinning.
  • False positives and false negatives are possible. In other words, embryos that are abnormal may test “normal,” and healthy embryos may mistakenly be diagnosed as abnormal and discarded.
  • If all embryos come back with poor results, there may be none to transfer.
  • Inconclusive results may occur. Also known as mosaic embryos, this is when some cells appear chromosomally normal and others do not. Some studies published in 2017 have found that mosaic embryos may correct themselves and can lead to a healthy pregnancy and baby.
  • Cryopreservation and subsequent thawing can lead to the loss of otherwise healthy embryos.
  • Some otherwise healthy embryos may not survive until Day 5 post egg retrieval.
  • Biopsy of Day 3 embryos may lead to embryo arrest, where the embryo stops developing.
  • PGT-M/PGT-A is not foolproof, and a child with a genetic disease or disorder may still result. Prenatal testing in addition to PGT-M/PGT-A is recommended for additional assurance.
  • Good preimplantation and prenatal testing do not guarantee the child won’t be affected by physical or mental handicaps of other kinds.
  • Risk of miscarriage may be lower with normal PGS embryos, but there still remains some risk of pregnancy loss.
  • Waiting for results and needing to make decisions about embryos with inconclusive results can be emotionally difficult.
  • The technology is so new that we don’t know for sure what the long-term effect may be on the children born after IVF with PGT-M/PGT-A. However, results look good according to a paper published in 2019.

How Much Does PGT-M/PGT-A Cost?

IVF is already expensive. Adding on the cost for PGT-M or PGT-A raises that price tag even higher. On average, preimplantation genetic testing adds between $3,000 and 7,000 to IVF treatment. Your costs for one IVF cycle with PGT-M/PGT-A may be between $17,000 and 25,000.

On top of this, you may need to pay for a frozen embryo transfer (FET) cycle. This will be an additional $3,000 to $5,000. Sometimes, patients want to plan the FET cycle immediately after the IVF cycle. This way, as soon as the results of the genetic screening come back, they can transfer any normal embryos without waiting an additional month.

However, a possible problem with this approach is that if there are no normal embryos to transfer, some of the FET costs will have been wasted. Any fertility drugs taken to suppress ovulation and prepare the uterus for implantation will have been taken without reason.

Waiting an additional month can be emotionally difficult, but may financially make more sense. With PGT-M, you may have expenses beyond the fertility treatment itself. PGT-M sometimes requires genetic testing of family members, and those costs won’t be included in your fertility clinic’s price quote and may not be covered by insurance.

A Word From Verywell

Genetic screening has helped families with a genetic disease or chromosomal translocations have a better chance of having a healthy child and avoiding passing down devastating illnesses. Genetic screening has also helped doctors improve embryo selection in elective single embryo transfer cycles.

Whether PGT-M/PGT-A can truly improve live birth rates beyond these situations is unclear. The technology is still rather new and constantly evolving. Using PGT-A to improve live birth rates in IVF when the technology isn’t specifically indicated is controversial.

Some doctors claim to see improved success, while others question whether it’s truly worth the additional costs and risks. Some think it should be offered to every IVF patient; others believe it should be offered rarely, in very specific cases.

It’s possible that PGT-A can help avoid transferring embryos that would have inevitably ended in miscarriage. However, this doesn’t mean the couple wouldn’t eventually have had a healthy pregnancy result with subsequent frozen embryo transfers (FET) from the same cycle.

For example, let’s say a couple gets three strong embryos. Let’s say they do PGT-A and discover two of the embryos are normal. One or two are transferred, and let’s say pregnancy occurs in one or two cycles. Now, let’s say that same couple decided not to do PGT-A and happens to transfer first the embryo with the chromosomal abnormality. That cycle will end in miscarriage. But they still have one or two more embryos waiting to be thawed and transferred and are likely to get a healthy baby from one of those embryos. (In a best odds situation, of course.)

According to a study published in 2016, the research says the odds of live birth are similar in each situation—with and without PGT-A. But there is an emotional cost of experiencing a miscarriage. PGT-A does not eliminate the odds of loss—though it does seem to reduce that risk.

Only you and your doctor can decide if IVF with PGT-M/PGT-A is right for your family. Before you decide, make sure you understand why your doctor recommends this assisted reproductive technology for you, the total costs (including cryopreservation and FET cycles), and the potential risks.

Was this page helpful?
21 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Society for Reproductive Medicine. Preimplantation genetic testing fact sheet. Updated 2014.

  2. USC Fertility. PGT-M (PGD) and PGT-A (PGS).

  3. Mandrioli D, Belpoggi F, Silbergeld EK, Perry MJ. Aneuploidy: a common and early evidence-based biomarker for carcinogens and reproductive toxicants. Environmental Health. 2016;15(1):97. doi:10.1186/s12940-016-0180-6

  4. Ly KD, Agarwal A, Nagy ZP. Preimplantation genetic screening: does it help or hinder IVF treatment and what is the role of the embryo?J Assist Reprod Genet. 2011;28(9):833-849. doi:10.1007/s10815-011-9608-7

  5. University of Nebraska Medical Center. Prenatal microarray. Updated March 8, 2019.

  6. National Institutes of Health. If a genetic disorder runs in my family, what are the chances that my children will have the condition? Updated May 12, 2021.

  7. Johns Hopkins Medicine. Common tests during pregnancy.

  8. Ikuma S, Sato T, Sugiura-Ogasawara M, Nagayoshi M, Tanaka A, Takeda S. Preimplantation genetic diagnosis and natural conception: a comparison of live birth rates in patients with recurrent pregnancy loss associated with translocation. PLOS ONE. 2015;10(6):e0129958. doi:10.1371/journal.pone.0129958

  9. Kahraman S, Beyazyurek C, Yesilipek MA, et al. Successful haematopoietic stem cell transplantation in 44 children from healthy siblings conceived after preimplantation HLA matching. Reproductive BioMedicine Online. 2014;29(3):340-351. doi:10.1016/j.rbmo.2014.05.010

  10. Ethics Committee of American Society for Reproductive Medicine. Use of preimplantation genetic diagnosis for serious adult onset conditions: a committee opinion. Fertil Steril. 2013;100(1):54-57. doi:10.1016/j.fertnstert.2013.02.043

  11. American Society for Reproductive Medicine. In vitro fertilization (IVF): What are the risks? Updated 2015.

  12. Brezina PR, Kutteh WH, Bailey AP, Ke RW. Preimplantation genetic screening (PGS) is an excellent tool, but not perfect: a guide to counseling patients considering PGS. Fertil Steril. 2016;105(1):49-50. doi:10.1016/j.fertnstert.2015.09.042

  13. Bayefsky MJ. Comparative preimplantation genetic diagnosis policy in Europe and the USA and its implications for reproductive tourismReprod Biomed Soc Online. 2016;3:41–47. doi:10.1016/j.rbms.2017.01.001

  14. Sato T, Sugiura-Ogasawara M, Ozawa F, et al. Preimplantation genetic testing for aneuploidy: a comparison of live birth rates in patients with recurrent pregnancy loss due to embryonic aneuploidy or recurrent implantation failure. Human Reproduction. 2019;34(12):2340-2348. doi:10.1093/humrep/dez229

  15. Evaluation and treatment of recurrent pregnancy loss: a committee opinion. Fertil Steril. 2012;98(5):1103-11. doi:10.1016/j.fertnstert.2012.06.048

  16. Lee HL, McCulloh DH, Hodes-Wertz B, Adler A, McCaffrey C, Grifo JA. In vitro fertilization with preimplantation genetic screening improves implantation and live birth in women age 40 through 43. J Assist Reprod Genet. 2015;32(3):435-44. doi:10.1007/s10815-014-0417-7

  17. Wang AY, Sullivan EA, Li Z, Farquhar C. Day 5 versus day 3 embryo biopsy for preimplantation genetic testing for monogenic/single gene defects. Cochrane Database Syst Rev. 2018;2018(12):CD013233. doi:10.1002/14651858.CD013233

  18. The American College of Obstetricians and Gynecologists. Preimplantation genetic testing. February 20, 2020.

  19. McCoy RC. Mosaicism in preimplantation human embryos: When chromosomal abnormalities are the normTrends Genet. 2017;33(7):448-463. doi:10.1016/j.tig.2017.04.001

  20. Greco E, Greco A, Minasi MG. Reassuring data concerning follow-up data of children born after preimplantation genetic diagnosis. Fertil Steril. 2019;111(6):1111-1112. doi:10.1016/j.fertnstert.2019.02.017

  21. Washington University Physicians. Preimplantation genetic testing-FAQ.