What it means

There is no single agreed definition. A common working definition is no clinical pregnancy after two or three transfers of good-quality embryos, taking the woman's age into account. The ESHRE good practice recommendations (2023) describe recurrent implantation failure as the situation in which embryos considered viable have failed to implant often enough, for that particular person, to justify further investigation. ESHRE suggests using each person's predicted chance of implantation, rather than a fixed number of transfers, to decide when to investigate.

Implantation depends on the embryo, on the lining of the uterus and on the interaction between them. ESHRE notes that much is still unknown about why it fails, and investigation does not always find a cause.

Who it is relevant to

Couples who have had several embryo transfers without a pregnancy
Couples whose pregnancies after IVF have repeatedly ended very early; these losses are also covered by the guidance on recurrent pregnancy loss
Couples deciding whether to continue treatment, change approach or consider other options

What ESHRE suggests looking at

Lifestyle, for both partners. Reviewing smoking, alcohol, caffeine, drugs and weight is recommended, since habits can change during treatment.

The embryo. Embryos with the wrong number of chromosomes have little chance of implanting, and such errors become more common with age; an embryo can look normal under the microscope and still be chromosomally abnormal. ESHRE suggests that PGT-A and a karyotype of both partners can be considered.

The uterus. A 3D ultrasound can be considered if it has not been done before, and hysteroscopy can be considered, especially when ultrasound suggests a problem inside the uterus. Imaging of the tubes can be considered if fluid in a tube (hydrosalpinx) is suspected. Assessment for chronic inflammation of the lining (chronic endometritis), with antibiotics if it is found, can be considered. If the lining stays thin, the hormone preparation is reviewed, and hysteroscopy can rule out scarring (Asherman's syndrome). Adenomyosis, endometriosis and fibroids are reassessed if new signs appear.

Blood tests. Testing for antiphospholipid antibodies is recommended when there are additional risk factors for blood clots, and can be considered otherwise. Thyroid function and progesterone levels can be considered.

The male partner. A review of lifestyle. ESHRE does not recommend sperm DNA fragmentation testing or sperm FISH analysis for implantation failure.

Questions worth asking your doctor

Given my age and my embryos, how unusual is it that the transfers so far have not worked?
Which of the recommended investigations have already been done, and which could change the plan?
For any proposed add-on: what is the evidence, how do ESHRE and the HFEA rate it, and what are its risks?
Would PGT-A, a different transfer approach or another option be worth discussing?

Risks and limits

Some investigations, such as hysteroscopy, are minor procedures with small risks of infection, bleeding or discomfort. Investigation does not always find a cause, and no test or treatment can promise that the next transfer will lead to a pregnancy. Treatments without evidence can add risk, delay and emotional strain, which is why ESHRE advises limiting investigations and treatments to those with a clear rationale and data suggesting benefit. The HFEA notes that, for most patients, routine cycles of proven treatment are effective without add-ons.

Common questions

After how many failed transfers should implantation failure be investigated?

There is no fixed number. Many specialists use two or three transfers of good-quality embryos, while ESHRE suggests basing the decision on each person's predicted chance of implantation, which depends heavily on age and embryo quality. Your doctor can advise when further investigation is reasonable.

Are immune tests and treatments useful?

ESHRE does not recommend NK cell or cytokine testing, or immune treatments such as intralipid infusions or IVIG, for implantation failure, and the HFEA rates IVIG and steroids red. Testing for antiphospholipid antibodies is the exception ESHRE supports when there are risk factors for blood clots.

Does investigation mean starting a new IVF cycle?

Not necessarily. Many couples already have frozen embryos, and the investigations often concern the uterus or the transfer itself. Whether a new cycle is needed depends on the findings and on the embryos available.

Is an endometrial receptivity test worth having?

ESHRE found the evidence insufficient to recommend routine use of the commercial tests, and the HFEA rates endometrial receptivity testing red. Research in this area continues.

Evidence basis: This page is based on the ESHRE good practice recommendations on recurrent implantation failure (2023), which rest largely on expert consensus because high-quality trials are few, and on the HFEA's ratings of treatment add-ons; where the evidence is limited, the page says so.

References

ESHRE good practice recommendations on recurrent implantation failure, Human Reproduction Open (ESHRE) (2023) — doi:10.1093/hropen/hoad023
Treatment add-ons with limited evidence, Human Fertilisation and Embryology Authority (HFEA) (2026) — hfea.gov.uk
Pre-implantation genetic testing for aneuploidy (PGT-A), Human Fertilisation and Embryology Authority (HFEA) (2023) — hfea.gov.uk

Written and reviewed by Dr. Ghina Shami, Consultant, Reproductive Medicine and Infertility · 13 October 2026 · How these pages are prepared

Recurrent implantation failure