Mitochondrial DNA Measurement in IVF Facts and Limits

The honest picture is more complicated. Measuring mitochondrial DNA is a real laboratory technique, and the biology behind it is genuinely interesting. But the question that matters to a patient is not whether the number can be measured. It is whether the number can safely guide a decision about which embryo to transfer or whether to discard an embryo. On that question, the evidence is still unsettled, and the major professional discussions have generally urged caution.

This article is written by the team behind our Georgia IVF center, clinic and hospital in Tbilisi and Batumi. We have organized it as an evidence ladder: we start with what mitochondria are, move up through what is measured, how it is measured and what studies have reported, and finish with what it all means for you in practice. We do not quote success rates, prices or percentages, because they would be misleading in a field where methods and thresholds differ from laboratory to laboratory. This page is general information, not medical advice. Your own decisions belong with your treating physician and a genetic counselor. No clinic can guarantee a pregnancy or a baby.

The Evidence Ladder: How to Read This Page

Why a Ladder

Medical claims are not all equally strong. A claim can rest on a basic biological idea, on laboratory measurements, on small studies, on larger studies, or on controlled trials that show an actual benefit to patients. Each step up is harder to reach and more trustworthy. When a clinic offers a test, it is worth asking which rung of the ladder the claim stands on.

Where Embryo Mitochondrial DNA Sits

Embryo mitochondrial DNA measurement is firmly on the lower and middle rungs. The biology is plausible, the measurement can be done, and a number of studies have reported associations. But the highest rung, which would be well designed trials showing that using the test improves the chance of a healthy baby per patient, has not been convincingly reached. Keeping this in mind will help you read the rest of this page.

How the Sections Are Arranged

Each rung below has its own section. If you only have a few minutes, read the sections titled “What Professional Bodies Advise” and “What It Means for a Patient.” If you want the full story, read from the start.

Rung One: What Mitochondria and Mitochondrial DNA Are

Powerhouses Inside Every Cell

Mitochondria are tiny structures inside nearly every human cell. Their best known job is to turn nutrients into usable energy, which is why they are often called the powerhouses of the cell. They also take part in signaling, in the handling of calcium and in controlling cell death. A developing embryo is a busy place, and its cells depend on mitochondria to supply energy for division and growth.

A Small Genome of Their Own

Unlike most cell parts, mitochondria carry a small genome of their own, called mitochondrial DNA, or mtDNA. It is a circular molecule that encodes a limited set of genes, mostly related to energy production. Most of the proteins mitochondria need are actually encoded by the DNA in the cell nucleus, so the two genomes work together. This is important when interpreting any measurement of mtDNA, because mtDNA alone does not describe mitochondrial health.

Why Eggs Carry So Many Copies

A human egg contains an unusually large number of mitochondria and therefore a large number of mtDNA copies. This stock is built up during egg development and is thought to support the embryo through its first days, before the embryo’s own cells can make large amounts of new mitochondria. During early divisions, the existing copies are shared among the growing number of cells. Because of this, the relative amount of mtDNA per cell changes as an embryo develops.

Inherited Through the Egg

Mitochondrial DNA is passed down almost entirely through the mother, because the sperm’s mitochondria are normally not carried into the lasting embryo. This maternal inheritance is why disorders caused by mtDNA variants are transmitted in a pattern different from conditions caused by nuclear genes. It is also the reason some reproductive technologies targeting mitochondria involve the egg, not the sperm.

Rung Two: What Is Actually Being Measured

Copy Number

When laboratories talk about embryo mitochondrial DNA measurement, they usually mean mtDNA copy number. This is an estimate of how much mtDNA is present in the sampled cells, relative to the amount of nuclear DNA in the same sample. The result is usually expressed as a ratio or a score, and the idea is that embryos with a very high or very low ratio might behave differently from embryos in a middle range.

Heteroplasmy and Mutation Load

A different question is whether the mtDNA carries disease causing variants, and in what proportion. A person or embryo can carry a mixture of normal and variant copies, which is called heteroplasmy. The proportion of variant copies, often called the mutation load, matters for mitochondrial disease. This is a separate diagnostic topic from copy number, and it is used in families with a known mitochondrial condition. Confusing these two uses is a common source of misunderstanding.

Other Samples

Researchers have also measured mtDNA in other places. They have studied the cells surrounding the egg, called cumulus cells, the egg itself, sperm, the culture medium in which an embryo has grown, and blood samples from adults, where mtDNA copy number has been explored as a general marker in aging and disease research. Each of these is a different measurement with a different meaning. The rest of this page concentrates on the embryo, because that is what patients usually ask about.

What the Number Is Not

The number is not a direct reading of an embryo’s energy output, not a measurement of how well its mitochondria function, and not a diagnosis of any condition. It is a quantity of DNA. How that quantity relates to embryo health is exactly what is still being studied.

Rung Three: How the Measurement Is Done

Starting With a Biopsy

Embryo mtDNA measurement is usually done on a small sample taken from the outer layer of a blastocyst, the stage reached around day 5 or 6 of development. This outer layer, the trophectoderm, will form the placenta rather than the baby. The same kind of biopsy is used for chromosome testing. In some laboratories, mtDNA is measured from the same sample used for chromosome analysis, which means the extra measurement does not require another biopsy.

Quantitative PCR and Sequencing

Two main approaches have been used. The first is quantitative PCR, a method that copies specific DNA sequences and measures how quickly the signal rises, which reflects how much of the target was present at the start. The second uses next generation sequencing data, in which the number of mtDNA reads is compared with the number of reads from nuclear DNA. Both approaches give a relative measure, not an absolute count of mitochondria.

Why Numbers Differ Between Laboratories

Many details influence the final score. The way the sample is amplified, the method used to normalize against nuclear DNA, the equipment, the software and the chosen cutoffs can all shift the result. Different laboratories have used different thresholds to label an embryo as having high or low mtDNA. A score from one laboratory therefore cannot simply be compared with a score from another. This lack of standardization is one of the reasons the findings are hard to compare across studies.

Biopsy Related Limits

A trophectoderm sample contains only a handful of cells and may not represent the whole embryo, especially if the embryo is mosaic. The timing of the biopsy, the number of cells taken and the stage of the embryo can all affect the measurement. These limits apply to any biopsy based test, and they matter even more when the quantity being measured changes naturally during development.

Rung Four: The Claim Behind the Test

The Basic Idea of a Score

The central claim is that embryos with an unusually high mtDNA copy number are less likely to implant or to lead to a live birth than embryos with a mid range value. Some groups have also looked at very low values. If the claim held up reliably, a laboratory could give each chromosomally normal embryo a score and suggest that high scoring embryos be placed lower in the order of transfer, or not transferred at all.

Biological Explanations Offered

Several explanations have been proposed. One is that a stressed embryo might make extra mtDNA copies as a response to energy demands or damage. Another is that extra copies might reflect problems with the egg’s mitochondria that the embryo tries to compensate for. A third relates to the idea that healthier embryos may keep a quieter metabolism, so that a high mtDNA content signals strain. These are hypotheses. None has been established as the reason behind any association found in the data.

Chromosomes Are a Complicating Factor

Chromosomally abnormal embryos tend to differ from normal ones in many measurable ways, and mtDNA content may be one of them. If a study mixes embryos with and without chromosome abnormalities, a difference in implantation could be driven by the chromosomes rather than by the mtDNA. Careful studies therefore look only at embryos that are chromosomally normal. This is harder to do, because it limits the number of embryos available for analysis.

Rung Five: What Studies Have Found

Early Reports

Early reports in the field described a striking pattern: embryos that failed to implant often had higher mtDNA measurements than embryos that led to births. These findings generated enormous interest, and some laboratories began offering mtDNA scoring to patients. Interest grew quickly because the idea was appealingly simple.

Later Studies

Later studies, including analyses from larger groups and from independent laboratories, did not always reproduce the pattern. Some found a weaker association. Some found no clear association once other factors were taken into account. A few suggested that the relationship might depend on the laboratory method, on the age of the patient or on the day of biopsy. The overall picture is of inconsistent findings, not of a clear and repeatable effect.

Why Results Are Hard to Replicate

Several reasons make replication difficult. Different methods produce different scores. Study populations differ in age and diagnosis. Biopsy practices and laboratory conditions vary. Many studies examine embryos retrospectively, after outcomes are known, which can create misleading patterns. Sample sizes of chromosomally normal embryos with known outcomes are often modest. For a test to guide decisions, the pattern should hold up when applied prospectively to new patients, and that is the standard that has been hard to meet.

What Would Strong Evidence Look Like

Strong evidence would come from carefully designed prospective studies, ideally randomized, in which some patients have embryos selected using the mtDNA score and others do not, and the live birth rate per patient is compared. It would also need an agreed method, a clear threshold and consistent results across laboratories. We are not aware of evidence at that level supporting routine clinical use, and readers should check for newer findings, because this is an active research area.

Rung Six: What Professional Bodies Advise

The General Position

Professional societies in reproductive medicine and embryology have generally taken a cautious position on embryo mtDNA quantification. In broad terms, their statements have said that the test has not been validated for routine clinical decisions, that it should not be used on its own to decide whether an embryo is discarded, and that its use belongs mainly in research settings with informed consent. Statements change as evidence accumulates, so please check the current position of the relevant societies and your national authority rather than relying on a summary here.

Why Caution Is Reasonable

Caution is not hostility to innovation. It reflects a simple risk. If a test wrongly labels a healthy embryo as poor, that embryo may be discarded, and for some patients it is the only chance. If a test wrongly reassures, a patient may place false confidence in an embryo that is not viable. A test that is not accurate and reproducible can do harm even when it is offered with good intentions.

Add Ons in General

mtDNA scoring is one of several laboratory add ons that appeal to patients. For any add on, the useful questions are the same: what exactly does it claim, what is the evidence that it improves the chance of a healthy baby per patient, what are the risks, and what does it cost? A reputable clinic will answer these questions plainly, including when the answer is that evidence is limited.

Rung Seven: What It Means for a Patient

Who Might Be Offered the Test

The test is most often presented to patients who have had repeated unsuccessful transfers, who have a small number of embryos, or who are looking for any additional information about an embryo before a transfer. These are people in a difficult emotional position, which makes it all the more important that the information they receive is balanced.

The Risk of Discarding a Viable Embryo

If a clinic uses an mtDNA score to rule out an embryo, there is a real chance that a good embryo may be set aside. Because no validated threshold exists, the cutoff used by a given laboratory may not correspond to a true difference in outcome for you. For patients with only one or two embryos, the consequences of a wrong label can be severe.

The Risk of False Reassurance

A favorable score may give the impression that an embryo is almost certain to implant. No laboratory score can promise this. Implantation depends on the embryo, the uterine lining, hormonal conditions, immune factors and chance. A low mtDNA number is not a guarantee, and a high one is not a verdict.

Cost and Time

Any additional test adds cost, and some require extra steps in the laboratory. Because this is a research stage test in many settings, it may not be covered by the base treatment fee. Ask for a written, itemized quotation and ask what happens, in practice and in cost, if the result is unclear or the test fails.

A Fair Way to Decide

A sensible approach is to treat embryo mtDNA scoring as an optional research related option rather than an essential part of treatment. If you decide to consider it, make sure you understand and agree in writing to what will be done with the result: will it rank embryos, or will it be used to exclude them? Ask whether the clinic would still transfer an embryo with an unfavorable score if it is your only embryo, and what the clinic’s own policy is. Agree on this before the test is run, not after.

Questions to Ask Your Clinic

Ask which method is used and in which laboratory the measurement is done. Ask how the threshold was chosen and whether it has been tested prospectively. Ask whether the test is offered as part of a research protocol with ethics approval and informed consent. Ask how the result will change which embryo is transferred. Ask what the clinic will do if the result and the embryo’s appearance disagree. Ask what the additional cost is, and ask for the evidence in writing. A transparent team will welcome these questions.

Other Meanings of Measuring Mitochondrial DNA

Diagnosing Mitochondrial Disease in Families

In families where a mother carries a disease causing mtDNA variant, laboratories can sometimes measure the proportion of variant copies in embryos. This is a diagnostic use, and its goal is to reduce the chance of transmitting a serious disorder. It is quite different from copy number scoring and is carried out with genetic counseling. The usefulness depends on the specific variant, on how much of it is present, and on how well a biopsy represents the embryo. This is a specialist area, and families should seek genetic counseling before any treatment.

Mitochondrial Replacement Techniques

Some countries have discussed or permitted highly regulated techniques that replace a mother’s mitochondria with those from a donor egg to avoid passing on serious mtDNA disease. These techniques are not mtDNA measurement and are available, if at all, only within strict legal frameworks in a small number of places. They are not a standard fertility treatment and are not offered in routine IVF clinics. If this topic concerns your family, seek specialist advice and check the law in the relevant country.

Research Uses in Eggs and Sperm

Researchers study mtDNA in eggs, in cumulus cells and in sperm as potential markers of reproductive aging or fertility problems. These studies are interesting, but they have not yet produced a test that is recommended for routine patient care. When you see these terms in advertising, ask whether the claim comes from research or from validated clinical practice.

Adult Blood Markers

Some research looks at mtDNA copy number in blood as a marker of aging or disease risk in adults. This is unrelated to embryo selection and should not be confused with fertility tests.

Cost Logic Without Numbers

The cost of an embryo mtDNA test, if it is offered, usually comes on top of the cost of the biopsy and chromosome analysis, and it may be priced per embryo or per cycle. We do not quote figures here, because they vary and would not be meaningful without knowing the laboratory and the method. Before agreeing to any add on, ask for a written itemized quotation. Check whether the package includes it or charges separately, what happens if the result is inconclusive, and whether there is any refund if the test cannot be completed. Be cautious with packages that promise better outcomes or improved success through scoring. No clinic can guarantee results.

Legal and Ethical Notes

Embryo Selection and the Law

Rules about what can be done to embryos differ from country to country. Some countries restrict genetic testing of embryos to specific medical reasons, and others regulate add ons and research uses closely. Before treatment, confirm that what is offered is legal where you are treated and understand how any embryo that is not transferred will be handled under your signed consent forms.

Treatment Abroad and Your Home Country

Treatment that is lawful in one country can have legal consequences in another. For example, in Türkiye, assisted reproduction is permitted only for married couples using their own eggs and sperm, and donor eggs, donor sperm, embryo donation and surrogacy are not allowed. Families treated abroad with donor cells or a surrogate may face difficulties with registration and medical follow up on return. If your plan involves any of these, take written legal advice from a lawyer in your home country before you begin.

Ethics of Offering Unproven Tests

Offering a test whose value is unproven raises ethical questions about informed consent, about the pressure patients may feel to try everything, and about commercial incentives. A responsible clinic explains clearly what is known and not known, separates research from routine care, and never implies that a score guarantees success.

Personal and Religious Values

Embryo selection and the handling of unused embryos raise personal and religious questions for some families. A medical center does not issue religious rulings. If this matters to you, speak to a qualified religious authority that you trust before deciding.

Georgia: Tbilisi and Batumi

Our teams in Tbilisi and Batumi work to the same medical and administrative protocols. If you are considering any embryo add on, including mitochondrial DNA scoring, you can ask in your first consultation, in writing, whether it is offered at all, whether it is part of a research protocol, which laboratory performs it and how a result would change your treatment. We would rather tell you honestly that a test lacks validated clinical use than sell it as a promise.

Tbilisi’s Shota Rustaveli International Airport lies roughly 17 kilometers from the city center. Batumi has its own airport very close to the city. The road distance between the two cities is about 350 to 370 kilometers, which takes roughly four and a half to six hours by car and about five to five and a half hours by train. Flights take under an hour but are not frequent, so check current schedules. Both cities offer a range of hotels and serviced apartments. A standard IVF cycle usually requires two to three weeks of stay, and part of the monitoring can often be coordinated with a doctor in your home country. Entry rules to Georgia depend on your citizenship, so check the current requirements before booking. The first consultation can be held online, and every patient is assigned a coordinator.

Frequently Asked Questions

What Is Mitochondrial DNA Measurement in IVF

It is a laboratory measurement, usually of how much mitochondrial DNA is present in a small sample of cells taken from an embryo, relative to nuclear DNA. It is sometimes called an mtDNA copy number or an mtDNA score.

Can the Test Tell Me Which Embryo Will Become a Baby

No. Studies have reported associations between mtDNA levels and outcomes, but the findings have not been consistent, and no validated threshold exists. The test cannot promise that an embryo will or will not implant.

Is the Test Part of Routine IVF

In general, no. Professional societies have taken a cautious position and have said that it is not validated for routine decisions. It may be offered as an add on or in a research setting.

Could the Test Cause Me to Lose a Good Embryo

That is a real concern. If a laboratory uses a score to exclude embryos without proven accuracy, a viable embryo might be set aside. Ask a clinic how results would be used before agreeing to the test.

Does the Test Replace Chromosome Testing

No. Chromosome testing and mtDNA measurement answer different questions. Many studies of mtDNA look only at chromosomally normal embryos in order to avoid confusion.

Is Mitochondrial DNA Measurement the Same as Mitochondrial Replacement

No. Mitochondrial replacement is a highly regulated technique to avoid passing on serious mitochondrial disease. Measurement is a laboratory test. They are separate topics.

Should I Ask for This Test

Only if, after an honest discussion with your doctor, you understand what it can and cannot show and how the result would be used. For most patients, the better questions are about the basics: egg and sperm quality, uterine health, the laboratory, chromosome testing where appropriate and a realistic treatment plan.

Is the Test Safe for the Embryo

The test itself uses a biopsy sample, and in experienced hands the biopsy is considered to carry a low risk to the embryo. The larger concerns are interpretive, not physical: what the number really means and how it is used.

Tbilisi or Batumi

Both teams follow the same protocols. Your coordinator will suggest the city that best fits your flights and treatment plan.

A Note About Hope and Data

There is a quiet pressure in fertility treatment to find a number that settles the matter. Hope looks for a measurement; data insists on caution. Between them sits every patient who has waited, wondered and tried again.

This page has tried to honor both. Hope is not foolish. It is the reason people begin treatment and the reason they continue. Data is not cold. It is the reason a clinic is able to tell a patient the truth. A good consultation holds these two together: it respects the wish for more information, and it refuses to pretend that a laboratory score can do more than the evidence allows.

If you would like to talk through any embryo test that has been suggested to you, including the ones described here, the team at our Georgia IVF center, clinic and hospital in Tbilisi and Batumi is ready to discuss it plainly and in writing. In your first message you only need to tell us the name of the test you have heard about and where you heard it. We will take it from there, without pressure and without promises we cannot keep.