Intended Parents

PGT-SR for IVF: How It Works and When Surrogacy May Be the Next Step

PGT-SR for IVF is a specialized type of embryo genetic testing used when an intended parent carries a structural chromosome rearrangement, such as a balanced translocation or inversion.

It helps identify embryos with chromosome results considered suitable for transfer, but it can’t tell you whether an embryo will implant or guarantee a healthy pregnancy.

If you’ve created suitable embryos but transfers repeatedly haven’t resulted in pregnancy, that difference becomes more relevant.

Your fertility specialist may need to look beyond the chromosome issue PGT-SR was designed to address and consider whether uterine, implantation or other pregnancy-related factors are affecting your results.

If carrying the pregnancy appears to be the remaining barrier, gestational surrogacy may become one of the options worth comparing.

What Is PGT-SR?

PGT-SR, or preimplantation genetic testing for structural rearrangements, tests embryos created through IVF for chromosome changes associated with known structural rearrangements such as translocations and inversions.

PGT-SR focuses on chromosome structure rather than every possible genetic condition. It is different from PGT-A, which primarily looks at whether an embryo has the expected number of chromosomes.

A balanced rearrangement means chromosome material has been reorganized without an overall gain or loss of genetic material.

Most people with a balanced rearrangement are healthy and may not know they carry one until chromosome testing is performed because of recurrent miscarriage, infertility evaluation, an affected pregnancy or family history.

Common structural rearrangements include:

Reciprocal translocations: Pieces of two chromosomes exchange places.
Robertsonian translocations: Genetic material involving certain chromosomes becomes rearranged through chromosome fusion.
Inversions: A section of a chromosome breaks and reinserts in the opposite direction.

The reproductive concern is that someone with a balanced rearrangement has a higher chance of creating embryos with missing or extra genetic material.

Embryos with an unbalanced rearrangement often don’t result in a live birth, although the outcome depends on the particular rearrangement and amount of chromosome material involved.

PGT-SR gives your fertility team more information about which embryos to consider for transfer. It does not make every embryo genetically normal or remove every other reason a transfer may not succeed.

Who Should Consider PGT-SR During IVF?

PGT-SR is generally considered when an intended parent has a known structural chromosome rearrangement that creates a risk of producing unbalanced embryos.

Situations that may lead to PGT-SR include:

A known balanced translocation or inversion
Recurrent miscarriages associated with chromosome abnormalities
A previous pregnancy affected by an unbalanced chromosome rearrangement
A family history that leads to chromosome testing
A structural rearrangement found during an infertility or genetic evaluation

A karyotype, also called chromosome analysis, is a blood test that can identify structural chromosome rearrangements.

Research on PGT for structural rearrangements explains how this testing is used to help identify embryos with chromosome results appropriate for transfer.

The specific rearrangement matters. The likelihood of producing embryos suitable for transfer can differ depending on the chromosome finding.

A genetic counselor can help translate the chromosome report into a more useful discussion about reproductive risk, embryo testing and how many embryos you may reasonably expect to be suitable for transfer.

What Does PGT-SR Actually Detect?

PGT-SR detects chromosome imbalances associated with known structural rearrangements and helps identify embryos considered appropriate for transfer.

The difference between balanced and unbalanced results matters here.

A balanced carrier has rearranged chromosome material without missing or extra genetic material and is typically healthy. An unbalanced embryo has missing or extra chromosome material, which can reduce the likelihood of a live birth or result in a chromosome-related condition.

PGT-SR doesn’t evaluate every genetic condition an embryo could have.

PGT-A, PGT-M and PGT-SR answer different genetic questions: PGT-A looks at chromosome number, PGT-M tests for a known single-gene condition and PGT-SR focuses on structural chromosome rearrangements.

Cleveland Clinic’s overview of preimplantation genetic testing explains that PGT examines a small number of cells taken from an embryo rather than testing every cell or predicting every possible pregnancy outcome.

A favorable PGT-SR result can be followed by a healthy pregnancy, but the test result itself can’t guarantee that outcome.

Prenatal diagnostic testing such as CVS or amniocentesis may still be discussed after pregnancy occurs.

For intended parents, a favorable PGT-SR result answers a specific chromosome question. It doesn’t predict every aspect of embryo development, implantation or pregnancy.

PGT-SR vs. PGT-A: What’s the Difference?

PGT-SR evaluates structural chromosome rearrangements, while PGT-A evaluates whether an embryo has the expected number of chromosomes.

PGT-SR is generally used when there is a known structural chromosome rearrangement. PGT-A looks for embryos with extra or missing chromosomes more broadly.

Test	What It Evaluates	Why It May Be Used
PGT-SR	Structural chromosome rearrangements, such as translocations and inversions	When a structural rearrangement creates a risk of embryos with missing or extra genetic material
PGT-A	Whether an embryo has the expected number of chromosomes	To identify embryos with extra or missing chromosomes

Progyny’s comparison of the different types of PGT provides additional context on how the three testing approaches differ.

The testing you need may depend on more than one factor.

A fertility specialist may recommend one or more forms of PGT based on genetic screening, family history and reproductive history.

Before testing begins, ask the genetics laboratory or fertility clinic exactly what your PGT-SR report will show and what each result category means for transfer decisions.

That is more useful than assuming every laboratory uses terms such as normal, balanced or suitable in exactly the same way.

How Does PGT-SR Affect IVF Success?

PGT-SR can improve embryo selection by helping identify embryos affected by the structural chromosome problem being tested, but it does not increase the number of eggs retrieved or embryos created.

A 2025 retrospective study compared 129 PGT-SR cycles with 419 PGT-A cycles.

After researchers matched the groups for relevant characteristics, fertilization rates were similar, but the PGT-SR group had a lower blastocyst development rate: 36.7% compared with 47.1% in the PGT-A group. Top-quality blastocyst development was 9.6% compared with 21.1%.

The type of structural rearrangement also affected the study’s results.

Among biopsied blastocysts, reciprocal translocation carriers had an average 45.7% normal/balanced blastocyst rate, while the group with other structural rearrangements had a rate of 89.9%.

That second group primarily included Robertsonian translocations, along with inversions and insertions.

There isn’t one balanced translocation IVF success rate that applies to every intended parent.

Outcomes can differ based on the particular rearrangement, the age of the egg source and whether “success” means obtaining a suitable embryo, achieving pregnancy or having a live birth.

The study figures above describe outcomes from one retrospective study, not your personal chance of pregnancy or live birth. Ask your fertility specialist how likely you are to obtain embryos considered suitable for transfer based on your particular rearrangement, age of the egg source and previous IVF results.

That estimate can help you decide whether another retrieval is likely to add meaningful options or whether your existing embryos already provide a reasonable path forward.

Why Can a PGT-SR Normal Embryo Still Fail to Implant?

A PGT-SR-suitable embryo can still fail to implant because the test evaluates a particular chromosome concern, while implantation depends on additional embryo, uterine and treatment factors.

A favorable chromosome result doesn’t establish that every other condition needed for pregnancy is present. Depending on your history and previous evaluation, your fertility specialist may consider factors such as:

1
Embryo characteristics not identified by the genetic testing performed
2
The limitations of testing a small sample of embryo cells
3
Fibroids, polyps, scar tissue or other uterine cavity abnormalities
4
Hydrosalpinx
5
Endometrial or other uterine factors
6
Embryo-transfer technique or timing
7
Other medical findings relevant to implantation or pregnancy

This discussion of PGT-normal embryo implantation provides additional context on why favorable PGT results don’t guarantee implantation.

One unsuccessful transfer isn’t enough to conclude that carrying the pregnancy is the problem.

After repeated unsuccessful transfers of embryos your clinic considers suitable, however, it becomes reasonable to ask what the treatment history is showing rather than assuming another identical transfer is automatically the next step.

Ask your reproductive endocrinologist what possible causes have already been evaluated, what findings remain unexplained and whether the evidence now points more strongly toward an implantation or pregnancy-related barrier.

When Does Surrogacy Make Sense After Failed IVF With Good Embryos?

Gestational surrogacy may make sense when suitable embryos remain but carrying or maintaining a pregnancy appears to be the primary barrier to a live birth.

PGT-SR and gestational surrogacy address different parts of the process. PGT-SR helps identify embryos for transfer.

Gestational surrogacy changes who carries the pregnancy.

This doesn’t necessarily mean IVF failed. IVF may have already produced embryos your fertility team considers appropriate for transfer.

If the remaining problem involves the uterus, recurrent implantation failure, recurrent pregnancy loss or a medical reason pregnancy shouldn’t be attempted, creating additional embryos may not address that problem.

Previously created PGT-SR-tested embryos may be considered for transfer to a gestational surrogate. Whether a particular embryo can move forward will depend on the fertility clinic’s review, the embryo-testing records and the medical requirements for transfer.

Genetic testing affects surrogacy when intended parents already have embryos available. Before making that decision, ask your reproductive endocrinologist whether another IVF treatment is likely to address a remaining embryo problem or whether the evidence points more strongly toward carrying the pregnancy.

We provide independent, educational guidance so intended parents can compare continued IVF, changes in treatment and gestational surrogacy based on the problem they are actually trying to solve.

Deciding What to Do with Existing Embryos? Find Out More About Surrogacy

If you have PGT-SR-tested embryos remaining after unsuccessful transfers, the next decision should focus on what your fertility specialist believes is preventing pregnancy and whether transferring an embryo to a gestational surrogate would address that problem more directly.

A surrogacy professional can explain how existing embryos may fit into a gestational surrogacy plan, what fertility and embryo records are typically reviewed and what medical steps generally occur before a surrogate is cleared for transfer.

When comparing surrogacy professionals, look at surrogate screening standards, financial protections, matching practices and medical coordination.

Ask what happens financially and procedurally if a match doesn’t move forward or an embryo transfer is unsuccessful.

If you’re considering whether your current embryos could support a surrogacy plan, you can explore gestational surrogacy options and connect with a professional who can explain what records are typically reviewed and what the process may involve.

That information gives you something concrete to compare with your fertility specialist’s recommendations.

The goal is not to move to surrogacy simply because transfers have failed, but to determine whether another transfer, a change in treatment or gestational surrogacy more directly addresses the remaining barrier.

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