Introduction
A negative pregnancy test after an embryo transfer can be devastating. When it happens more than once, many patients understandably start asking: “Why is this happening?” and “What should we check before trying again?”
Repeated implantation failure, also called recurrent implantation failure or RIF, is usually used to describe repeated failure to achieve a pregnancy after transfer of embryos expected to have a reasonable chance of implanting. However, it is not as simple as saying “two failed transfers means something is wrong”.
Embryo transfer can fail because of embryo factors, uterine factors, endometrial timing, sperm factors, transfer technique, medical issues, or chance. In many cases, especially when embryos have not been chromosome-tested, the most common explanation is still embryo biology.
This article explains what repeated implantation failure means, what I usually review before another embryo transfer, and why investigation should be thoughtful rather than a rush into every possible IVF add-on.
💡Note: This blog is general educational information only and does not constitute personalised medical advice. Please consult with a fertility specialist to discuss your individual situation.
What Is Repeated Implantation Failure?
There is no perfect universal definition of repeated implantation failure.
Some people use the term after two or three failed embryo transfers. Others define it based on the number of good-quality embryos transferred, the age of the person who provided the eggs, whether embryos were tested, and the expected chance of pregnancy.
A failed transfer after one embryo does not automatically mean implantation failure. Even a good-looking embryo may not have the right chromosome number or biological potential to become a baby.
I prefer to look at repeated implantation failure as a clinical signal, not a rigid label. The question is not simply: “How many transfers have failed?”
💡The better question is: “Given your age, embryo quality, embryo testing status, uterine findings, transfer details, and treatment history, is the outcome more than we would expect by chance?”
Implantation Failure vs Miscarriage
Implantation failure and miscarriage are related but not the same.
Implantation failure usually means there is no pregnancy detected after embryo transfer, or sometimes only a very early biochemical pregnancy that does not progress. Miscarriage means a pregnancy has implanted but then stops developing.
This distinction matters because the investigations may differ. Recurrent miscarriage may prompt specific assessment for miscarriage-related factors, while repeated implantation failure often starts with reviewing embryo potential, uterine cavity, transfer timing, and endometrial preparation.
Some patients experience both failed transfers and miscarriages. In that situation, the assessment needs to consider both implantation and pregnancy loss.
Why Embryo Transfers Fail
An embryo transfer can fail even when everything appears technically correct.
For implantation to result in an ongoing pregnancy, several steps need to happen. The embryo needs to have developmental potential. The uterus needs to be structurally suitable. The endometrium needs to be prepared and synchronised with the embryo. The transfer needs to place the embryo gently in the right location. Then biology still needs to work.
This is why it can be misleading to assume the uterus “rejected” the embryo. Sometimes the embryo was never capable of implanting. Sometimes the uterine environment was not ideal. Sometimes there are treatable issues. Sometimes no clear explanation is found.
The aim of review is to identify correctable factors without overpromising that every failed transfer has a fixable cause.
First Step: Review the Embryos
Before adding new tests or treatments, I usually start by reviewing the embryos.
Important questions include: how old was the person providing the eggs, how many eggs were collected, how many fertilised, how many embryos reached blastocyst stage, what were the embryo grades, were embryos day 5 or day 6, did they survive thawing well, and were they chromosome-tested?
If embryos were not tested with PGT-A, chromosome abnormality remains a common reason for failed implantation, especially with increasing age. A visually good-grading embryo can still be chromosomally abnormal.
If embryos were PGT-A tested and euploid, the discussion changes. A euploid embryo has a higher chance of implantation, but it still does not guarantee pregnancy. PGT-A is not 100% accurate and cannot exclude every genetic, structural or developmental issue.
The number of embryos matters too. Failed transfer of one or two embryos may still fall within expected probability. Repeated failure of several good-quality or euploid embryos deserves closer review.
Reviewing the Transfer Cycle
The embryo transfer cycle itself should also be reviewed.
I look at the endometrial lining, hormone levels, timing of progesterone, whether ovulation was clear in a natural or modified natural cycle, medication adherence in a medicated cycle, and whether the transfer was technically straightforward.
In frozen embryo transfer cycles, progesterone timing is particularly important. The embryo and endometrium need to be synchronised. Too little progesterone exposure, incorrect timing, missed doses, absorption issues, or uncertainty about ovulation timing can all matter.
The transfer procedure also matters. A difficult transfer, cervical stenosis, unexpected uterine angle, or uncertainty about placement may prompt a plan to adjust technique, perform a trial transfer, use ultrasound guidance, or assess the cervix and uterine cavity more carefully before the next attempt.
Checking the Uterine Cavity
A normal-looking uterus on standard ultrasound is reassuring, but it does not always exclude small cavity problems.
Before repeated embryo transfer, it may be appropriate to assess the uterine cavity more closely, especially if this has not been done recently. Options may include saline infusion ultrasound, HyCoSy, hysteroscopy, or other imaging depending on the clinical situation.
Findings that may matter include endometrial polyps, submucosal fibroids, adhesions, a uterine septum, retained tissue, fluid in the cavity, or significant cavity distortion.
If a polyp, adhesion or submucosal fibroid is present, treating it before another embryo transfer may be sensible. The goal is not to perform procedures for everyone, but to make sure there is not a correctable structural problem being missed.
Hydrosalpinx and Fallopian Tube Fluid
Even in IVF, fallopian tubes can still matter.
A hydrosalpinx is a fluid-filled, damaged fallopian tube. Fluid from a hydrosalpinx can leak back into the uterus and may reduce implantation chances. If a hydrosalpinx is seen or suspected, treatment before further embryo transfer may be recommended.
This is one reason tubal history remains relevant even when embryos are transferred directly into the uterus. Previous pelvic infection, endometriosis, ectopic pregnancy, or tubal surgery may increase the chance of tubal issues.
Endometrial Thickness and Preparation
The endometrium, or uterine lining, is often monitored before embryo transfer.
A very thin lining can be associated with lower implantation rates, although there is no single measurement that perfectly predicts success. Lining pattern, response over time, hormone exposure, and previous cycle history all matter.
If the lining has repeatedly been thin, I may review the transfer protocol, oestrogen dosing and route, uterine blood flow factors, previous surgery, adhesions, and whether hysteroscopy is needed.
Sometimes changing from medicated to natural-cycle transfer, or from natural to medicated preparation, may be considered depending on ovulation pattern, lining response, and previous cycle details.
Chronic Endometritis
Chronic endometritis is persistent low-grade inflammation of the uterine lining. It is different from endometriosis.
It may not cause symptoms and is usually diagnosed through endometrial biopsy, sometimes with specific staining for plasma cells. Its role in implantation failure is still being studied, but testing may be considered in selected patients, particularly if there have been repeated failed transfers, recurrent miscarriage, abnormal bleeding, or risk factors for infection.
If chronic endometritis is diagnosed, treatment usually involves antibiotics, then followed by repeat assessment depending on the situation and clinic practice.
💡This is not a test I use automatically for every patient after one failed transfer, but it may be reasonable in a targeted investigation plan.
Blood Tests and General Health
General health can affect fertility treatment and pregnancy. Relevant factors include thyroid function, prolactin, diabetes or insulin resistance, vitamin D, full blood count, autoimmune history, clotting history, weight, smoking, medications, and other medical conditions.
However, broad “screen everything” blood testing is not always helpful. Some abnormal results do not change management. Some tests create anxiety without improving outcomes.
The most useful investigations are those linked to a clear clinical question: “If this result is abnormal, what would we do differently?”
Immune Testing and IVF Add-Ons
After repeated failed transfers, many patients search online and find immune tests, natural killer cell testing, intralipids, steroids, endometrial receptivity testing, platelet-rich plasma, endometrial scratching, and other IVF add-ons.
I understand why these are appealing. When transfers keep failing, patients want something new to try.
The difficulty is that many add-ons have limited, conflicting, or low-quality evidence. Some may add cost, side effects, inconvenience, or false hope without clearly improving the chance of a baby.
That does not mean every additional treatment is always wrong. It means we need to be honest about what is proven, what is uncertain, and what may cause harm.
💡 In my practice, I try to avoid adding treatments simply because “we should do something”. I prefer to identify a plausible problem first, then consider whether a test or treatment is likely to change the plan.
When PGT-A May Be Discussed
PGT-A may be discussed if repeated transfers have involved untested embryos, particularly where age-related chromosome abnormality is a likely contributor.
PGT-A does not increase the number or quality of embryos. It does not guarantee pregnancy. However, it may help select embryos with the expected chromosome number and may reduce time to pregnancy or miscarriage risk in selected patients.
The decision depends on age, embryo number, previous transfer history, cost, values and whether testing would change management.
You can read more about the advantages and limitations of PGT-A in this blog article.
Practical Takeaways
Repeated implantation failure does not have one simple definition.
One failed transfer does not automatically mean something is wrong.
The most important first step is to review the embryo, the transfer cycle, and the uterine environment.
Embryo chromosome abnormality is a common reason transfers fail, especially with increasing age and untested embryos.
Uterine cavity problems such as polyps, adhesions, fibroids, fluid, or hydrosalpinx should be considered before repeated transfers.
Progesterone timing, lining preparation, and transfer technique may also need review.
IVF add-ons should be approached carefully because many remain unproven.
Final Thoughts
Repeated implantation failure is distressing, but it should be approached calmly and systematically.
The answer is not always more tests, more medication, or more add-ons. The first step is to review the embryo, the uterus, the endometrial preparation, progesterone timing, transfer technique, and the overall fertility picture.
Sometimes a clear issue is found and corrected. Sometimes the most likely explanation is embryo biology or chance. Sometimes the best plan is to adjust the transfer protocol. Sometimes it is to create more embryos, consider PGT-A, or move forward with a clearer understanding of the uncertainty.
If you have had repeated failed embryo transfers and want to understand what should be reviewed before another transfer, get in touch and I can help you work through the next step calmly and practically.
Disclaimer: This information is general in nature and does not replace medical advice. Please consult with your treating specialist for individualised guidance.