Why IVF Fails: Common Causes and What to Do Next

A failed IVF cycle is a particular kind of grief. Unlike other fertility losses, it arrives after weeks of injections, monitoring appointments, early mornings in waiting rooms, and the careful optimism that builds between egg retrieval and the two-week wait. When the result is negative, couples are left not only with the outcome but with the question they cannot stop asking: why?

Most of the time, that question does not have a single answer. And sometimes, the honest answer is that the cycle did not fail because of a problem that could have been caught or fixed. It failed because roughly 50 to 70% of all human embryos carry chromosomal abnormalities that prevent implantation, a biological reality that exists in natural conception as well as IVF and that no stimulation protocol, laboratory technique, or clinical decision can change.

The distinction between those two explanations, a correctable cause and a statistical inevitability, is the most important thing a couple can understand after a failed cycle. It determines whether the right next step is an investigation, a protocol change, or simply trying again with better information.

Why Do Most IVF Cycles Fail on the First Attempt?

The most common reason an IVF cycle fails is surprisingly simple: the embryo was chromosomally abnormal.

This condition, known as embryo aneuploidy, means the embryo carries an incorrect number of chromosomes. In most cases, these embryos fail to implant. In others, implantation occurs briefly before ending in an early miscarriage.

One of the difficult realities of IVF is that abnormal embryos often look completely normal in the lab. A high-quality day-5 blastocyst may still be aneuploid, meaning standard embryo grading alone cannot reliably determine whether an embryo is genetically viable.

The likelihood of embryo aneuploidy increases sharply with maternal age.

• In women under 35, approximately 30–40% of blastocysts are aneuploid
• By age 40, that proportion rises to more than 70%

This is one of the main reasons IVF success rates decline after 35, even when ovarian stimulation, fertilisation, and embryo development appear normal. In many failed cycles, the issue is not that embryos failed to develop in the laboratory. The problem is that the embryos were never genetically capable of producing an ongoing pregnancy.

A widely cited 2021 Human Reproduction study by Pirtea et al. found that three consecutive transfers of single euploid blastocysts (embryos confirmed as chromosomally normal through PGT-A testing) resulted in a cumulative implantation rate of 95.2%.

The implication is significant. When the embryo's chromosomal status is confirmed as normal, implantation succeeds in the vast majority of cases.

For this reason, many fertility specialists now view repeated implantation failure without confirmed euploid embryos primarily as an embryo quality problem rather than a uterine or endometrial disorder.

What Is Recurrent Implantation Failure and How Is It Defined?

Recurrent implantation failure (RIF) is a term used frequently in fertility clinics and almost as frequently without a consistent definition. The ESHRE Working Group on Recurrent Implantation Failure published good-practice recommendations in 2023, defining RIF as the absence of a successful pregnancy following the transfer of three or more good-quality embryos in a woman under 40.

But in practice, the situation is often more complicated than the label suggests. 

Data from Pirtea et al. and subsequent euploid embryo transfer studies indicate that true implantation failure (where implantation repeatedly fails despite the transfer of confirmed chromosomally normal embryos) affects fewer than 5% of IVF patients.

This distinction matters because many couples diagnosed with "RIF" have never undergone transfer with confirmed euploid embryos. In those cases, repeated IVF failure is more likely to reflect embryo aneuploidy than a problem with implantation itself.

In other words, many presumed implantation failures are actually embryo quality failures under a different name.

That difference has important implications for treatment planning. If the embryo's chromosomal status remains unknown, the next evidence-based step is often further embryo assessment or PGT-A testing rather than immediately proceeding to extensive uterine investigations.

According to data presented at ESHRE 2025, approximately 10% of women undergoing embryo transfer are described clinically as having recurrent implantation failure. However, for many of these patients, the most evidence-supported next step is:

• PGT-A testing of remaining embryos
• A new IVF stimulation cycle aimed at producing euploid embryos
• Reassessment of embryo quality before pursuing complex implantation-focused therapies

As understanding of embryo genetics improves, fertility specialists increasingly recognise that implantation failure and embryo failure are not always the same thing.

When Should a Uterine Investigation Follow a Failed Cycle?

After one or two failed IVF transfers involving morphologically good embryos, the most informative next step is often not a uterine investigation, but embryo testing.

If the embryos have not undergone chromosomal testing, PGT-A can help determine whether the failures were due to embryo aneuploidy rather than to implantation. When euploid embryos are identified, the next transfer becomes a confirmed embryo quality selection rather than a statistical probability exercise.

A uterine investigation becomes more relevant once embryo quality has been clarified and implantation continues to fail. This is generally considered in several situations.

Failed Transfer of Euploid Embryos

The strongest indication for uterine investigation is repeated failure of confirmed chromosomally normal embryos to implant. If two or more euploid embryo transfers fail, the clinical focus shifts more legitimately toward the uterine environment rather than embryo quality.

Structural Uterine Abnormalities

Ultrasound or hysterosalpingography may identify anatomical abnormalities that interfere with implantation, including:

• Endometrial polyps
• Submucosal fibroids
• Uterine septum
• Intrauterine adhesions

Many of these conditions are treatable with hysteroscopy.

A 2024 literature review found that hysteroscopic correction of intracavitary abnormalities before IVF was associated with improved implantation rates in subsequent cycles.

Thin Endometrium

Endometrial thickness also plays an important role in implantation success. When the endometrium consistently measures below 7 mm during cycle preparation, implantation rates decline regardless of embryo quality.

Some fertility centres now use platelet-rich plasma (PRP) therapy in selected patients with persistently thin endometrium. In this approach, PRP is instilled directly into the uterine cavity to improve endometrial receptivity.

A 2025 study presented in Human Reproduction reported significantly higher biochemical and clinical pregnancy rates in recurrent implantation failure patients treated with intrauterine PRP compared to controls. The effect appeared strongest in women with previous failed euploid embryo transfers.

The broader principle is important: uterine investigation becomes most valuable once embryo-related causes of failure have already been reasonably excluded.

What Is the Endometrial Receptivity Analysis (ERA) and Who Actually Needs It?

ERA analyses a small biopsy of the endometrial lining to identify a woman's precise window of implantation (WOI), the narrow period during which the endometrium is receptive to an embryo. 

Standard frozen embryo transfer protocols are based on the assumption that most women become receptive at roughly the same point in a hormonally prepared cycle. ERA attempts to determine whether a patient's receptive window occurs earlier or later than expected, and adjusts embryo transfer timing accordingly through personalised embryo transfer (pET).

Who May Benefit From ERA?

The evidence supporting ERA is strongest in a relatively specific patient group:

• Women with two or more failed transfers of good-quality embryos
• Patients with a normal uterine cavity
• Cases where no obvious explanation for implantation failure has been identified

In these patients, a displaced window of implantation may contribute to repeated failed transfers despite apparently good embryo quality.

Is ERA Recommended for Everyone?

Not necessarily. ERA has increasingly been marketed as a routine IVF add-on, but current evidence does not support universal use, particularly in patients undergoing their first or second IVF cycle without confirmed euploid embryo failures.

The broader concern is that many failed IVF cycles are still caused primarily by embryo aneuploidy rather than problems with endometrial timing. In those situations, ERA may add cost and complexity without meaningfully improving outcomes.

The 2023 ESHRE recommendations clearly reflect this position. The guidelines advise that add-on investigations, such as ERA, should be used selectively rather than routinely, and be reserved for patients whose clinical history genuinely justifies deeper implantation-focused investigation.

In practice, ERA is most relevant after embryo-related causes of failure have already been carefully evaluated.

What Is Chronic Endometritis and How Does It Affect Implantation?

Chronic endometritis (CE) is a persistent, low-grade inflammation of the uterine lining caused by microbial colonisation of the endometrial cavity. Unlike acute pelvic infections, CE is often subtle and easily missed. Many women have no obvious symptoms, transvaginal ultrasound findings are usually normal, and routine fertility investigations may not detect it.

Diagnosis typically requires an endometrial biopsy with immunohistochemical staining for CD138-positive plasma cells, the key marker for confirming chronic endometritis.

The condition has attracted increasing attention in reproductive medicine because of its association with recurrent implantation failure (RIF) and poor IVF outcomes.

One published comparison found:

• A clinical pregnancy rate of 20% in RIF patients with chronic endometritis
• A pregnancy rate of 46.9% in RIF patients without CE

The proposed mechanism is biological rather than structural. Chronic inflammation appears to disrupt endometrial receptivity by altering the local immune environment and interfering with the synchronisation required between the embryo and the uterine lining during implantation.

How Is Chronic Endometritis Treated?

Treatment usually involves a course of targeted antibiotics, often guided by endometrial culture results. Commonly used antibiotics include:

• Doxycycline
• Amoxicillin-clavulanic acid

Because persistent infection can continue despite symptom improvement, many fertility specialists confirm treatment success with a repeat biopsy after therapy.

Studies have consistently shown improved implantation and pregnancy rates in previously CE-positive patients following successful treatment.

What Are EMMA and ALICE Tests?

When standard cultures are inconclusive, some clinics use advanced molecular testing of the endometrial microbiome. These include:

• EMMA (Endometrial Microbiome Metagenomic Analysis): Evaluates the balance of beneficial and non-beneficial bacteria within the uterine environment
• ALICE (Analysis of Infectious Chronic Endometritis): Screens for bacterial pathogens associated with chronic endometrial inflammation

These tests aim to identify microbiome-related implantation issues that may not appear on routine cultures or standard pathology testing.

What Role Do Immunological Factors Play in Repeated Failure?

Immune implantation dysfunction is one of the most debated areas in reproductive medicine. It is also one of the most commercially overextended. The distinction matters because while immune factors may contribute to implantation failure in selected patients, the evidence supporting many immune-based treatments remains limited.

During normal implantation, the maternal immune system must tolerate the embryo despite recognising it as partially foreign. This process depends on a highly regulated balance of immune activity within the endometrium, involving:

• Natural killer (NK) cells
• T-regulatory (Treg) cells
• Cytokine signalling pathways

When this balance becomes disrupted, the uterine environment may become less receptive to implantation.

One area of investigation involves testing for endometrial NK cells, usually performed on a biopsy obtained during the mid-luteal phase. Elevated uterine NK cell activity has been proposed as a possible contributor to repeated implantation failure in some patients, particularly after failed euploid embryo transfers.

In selected cases, specialist fertility centres may use treatments such as:

• Low-dose prednisolone
• Intralipid infusions
• Tacrolimus

However, the evidence supporting these therapies remains mixed. Most immune-based fertility treatments have not yet been validated through large randomised controlled trials, and the 2023 ESHRE recommendations continue to classify many immunological add-ons as experimental outside of clearly defined immune pathology.

For that reason, most specialists recommend caution before starting immune treatment protocols without prior diagnostic evaluation. Immune therapies are most appropriately considered in carefully selected patients rather than applied routinely after failed IVF cycles.

How Can Couples Reduce the Risk of IVF Failure?

Not every failed IVF cycle is preventable. Embryo chromosomal abnormalities remain the single biggest reason implantation does not occur, particularly as maternal age increases. However, careful evaluation and evidence-based treatment planning can significantly improve the chances of success over multiple cycles.

Optimise Embryo Quality

Because embryo aneuploidy is the leading cause of IVF failure, improving embryo selection is often the most important step. Depending on the clinical situation, specialists may recommend:

• PGT-A testing to identify chromosomally normal embryos
• Adjustments to ovarian stimulation protocols
• Addressing sperm DNA fragmentation or male factor infertility
• Lifestyle changes that reduce oxidative stress, including smoking cessation and weight optimisation

In selected cases, using testicular sperm for ICSI may improve outcomes when ejaculated sperm shows persistently elevated DNA fragmentation.

Investigate Repeated Implantation Failure Properly

After multiple failed cycles, further IVF attempts without additional investigation may repeat the same outcome. A proper workup may include:

• Diagnostic hysteroscopy
• Evaluation for chronic endometritis
• Assessment of endometrial thickness and receptivity
• Review of previous embryology and stimulation protocols
• ERA testing in carefully selected patients with failed euploid transfers

The key is to identify whether the primary issue is embryo quality, uterine receptivity, or treatment strategy.

Choose the Right IVF Centre

Laboratory quality plays a major role in IVF success rates. Embryo culture conditions, embryologist experience, freezing techniques, and quality control standards all influence outcomes, particularly in complex fertility cases.

Couples with repeated failed cycles may benefit from seeking a second opinion or consulting centres with specific experience in:

• Recurrent implantation failure
• Male factor infertility
• Advanced embryology
• Euploid embryo transfer programs

Improve General Reproductive Health

While lifestyle changes cannot reverse age-related chromosomal abnormalities, they may still improve overall reproductive health and treatment response. Most fertility specialists recommend:

• Maintaining a healthy body weight
• Avoiding smoking and excessive alcohol use
• Managing chronic medical conditions
• Correcting vitamin deficiencies where appropriate
• Following medically supervised treatment plans rather than relying on unproven fertility supplements or add-ons

The goal is not to eliminate all risk of IVF failure (which is impossible) but to maximise the probability that each transfer involves the best possible embryo in the most receptive environment.

What Should Couples Do After Two or Three Failed Cycles?

After multiple failed IVF cycles, the next step should not automatically be another transfer. The priority should be a proper investigation into why the previous cycles failed.

A comprehensive post-failure workup at a specialist fertility centre may include:

• PGT-A testing of remaining frozen embryos
• Chromosomal assessment in a new IVF cycle before transfer
• Diagnostic hysteroscopy to confirm the uterine cavity is anatomically normal
• Endometrial biopsy with CD138 immunohistochemistry to rule out chronic endometritis
• ERA testing if two or more confirmed euploid embryo transfers have already failed

The goal is to determine whether the repeated failures are primarily due to embryo quality, uterine factors, endometrial receptivity, or the treatment protocol itself.

Reviewing the IVF Protocol

Repeated failed cycles also warrant a detailed review of the IVF protocol used. Factors that may influence outcomes include:

• Ovarian stimulation strategy
• Trigger timing
• Endometrial preparation
• Luteal phase support
• Fresh versus frozen embryo transfer approach

In some patients, outcomes improve significantly when a fresh transfer cycle is converted to a freeze-all strategy with transfer performed in a later, hormonally controlled cycle.

When Should Couples Consider Changing Clinics?

Changing fertility clinics is also a reasonable consideration after repeated unsuccessful cycles, particularly if the same protocol has been repeated multiple times without modification.

Different centres may offer:

• More advanced embryology laboratories
• Alternative stimulation approaches
• Greater experience with recurrent implantation failure
• Broader diagnostic evaluation
• Different perspectives on treatment planning

Sometimes the most important change is not the patient's biology, but the way the case is being approached. For couples facing repeated IVF failure, a fresh evaluation from a specialist centre can occasionally identify factors that were previously overlooked.

What Questions Should Couples Ask After a Failed Cycle?

1. Were the transferred embryos tested for chromosomal normality? If not, is PGT-A testing available for the remaining embryos or for the next cycle?
2. Has a diagnostic hysteroscopy been performed to confirm the uterine cavity is free of polyps, adhesions, submucous fibroids, and septum?
3. Has an endometrial biopsy been taken and tested for chronic endometritis using CD138 immunohistochemistry, and if positive, what is the antibiotic protocol?
4. If two or more euploid embryo transfers have failed, has ERA testing been discussed to assess whether the window of implantation is displaced?
5. Does the centre distinguish between embryo-related failure and genuine endometrial-factor failure before recommending immune treatment add-ons?
6. What specific changes to the stimulation or transfer protocol are being proposed for the next cycle, based on what was learned from this one?

Conclusion

Most couples who eventually achieve a live birth through IVF do not succeed on the first attempt. The global IVF data is consistent on this point. A single failed cycle is not evidence of an unsolvable problem. It is the beginning of a diagnostic process that, when conducted properly, identifies what needs to change.

The couples who stay stuck are usually those who repeat the same cycle with the same protocol and the same untested embryos and expect a different result. The couples who progress are those who treat each failed cycle as data, ask what it revealed, and change something specific in response.

Take the Next Step

If you are considering fertility treatment abroad or seeking a second opinion after unsuccessful IVF cycles, fill out the form to speak with a Qonaq Health expert. Our team can help you connect with experienced fertility specialists, compare treatment options, and arrange consultations with internationally recognised IVF centres. 

Getting the investigation right costs one consultation. Getting it wrong costs another cycle.

Disclaimer: This article provides general educational information about failed IVF cycles and investigation options. It does not constitute medical advice and must not replace a consultation with a qualified reproductive endocrinologist or fertility specialist. Individual causes of implantation failure vary and require clinical assessment. Couples should consult a fertility specialist before making any decisions about further treatment or investigation.