An open letter to the HFEA about Choose a Fertility Clinic by Professor Dusko Il

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Comment
The following letter has been sent to Peter Thompson, chief executive of the Human Fertilisation and Embryology Authority (HFEA).

Dear Peter,

Thank you for your recent communication and the interim publication of Choose a Fertility Clinic (CaFC) metrics on 29 May. We acknowledge the challenge of presenting meaningful outcome data in a rapidly evolving clinical landscape, and we appreciate the HFEA's intent to offer patients more timely information.

That said, we must raise serious concerns about the continued use of live birth per embryo transferred as the headline measure.

Focusing on live births per embryo transferred, rather than per cycle started or per patient, omits key aspects of the treatment journey.

This metric can unintentionally:

Favour clinics that selectively transfer only high-quality embryos, often after multiple freeze-all cycles where embryos of average quality are not even given chance and discarded, thereby inflating apparent success rates.
Allow exclusion of patients with poorer prognoses, including those whose cycles are cancelled or result in no embryos for transfer – particularly common in low ovarian reserve.
Create space for clinics to implicitly attribute success to adjunctive treatments or add-ons (such as PGT-A, IVIG, or immune testing), when in fact their reported outcomes benefit from methodological artefacts rather than evidence-based efficacy.
The statement on the HFEA website that differences are due to 'chance' is misleading in this context.

The data being published from highly heterogeneous populations and practices.

Clinics do not all treat the same mix of patients; they can (and do) differ in their:

Patient age profiles.
Use of donor gametes.
Use of PGT-A.
Patient selection (poorer prognosis patients may be shifted into 'natural IVF' category allowing to remove this group of patients from denominator).
Clinical protocols (multiple cycle banking for patients with poor reserve).
Inclusion or exclusion of certain types of cycles in reported denominators.
To suggest that differences of a significant percentage points are simply 'chance' without mentioning that systematic biases in patient selection and reporting drive these differences is non-scientific and risks misleading patients.

The mixing of different subpopulations into one 'success rate' is a serious methodological flaw.

Reporting an aggregate 'live birth per embryo transfer' without appropriate stratification:

Rewards clinics who heavily filter patients pre-transfer.
Hides poor performance in the stimulation, fertilisation, or embryo development phases.
Fails to account for the fact that many patients (especially older or poorer prognosis) never reach embryo transfer.
The current system ignores the fundamental problem of:

Denominator manipulation – by excluding failed cycles and those who never reach embryo transfer, a clinic can appear to outperform others simply by being more selective.
The PGT-A disclaimer is insufficient and misleading.

While the website does mention that PGT-A may influence success rates, the current wording is not enough to prevent patients from perceiving that PGT-A clinics are 'better'.

Critically, it fails to mention that:

Many patients are excluded from reported success rates entirely if their embryos are deemed 'abnormal' and no transfer occurs.
PGT-A outcomes should be reported separately and transparently (as per latest good practice recommendations), with success rates per cycle started or per patient, not just per embryo transfer.
Without full transparency on how many cycles never result in transfer, the success rates can appear artificially high.

We urge the HFEA to consider the following immediate steps.

The presentation of data in current format needs to be suspended.
Live birth rate needs to be reported per cycle started (multiple pregnancy rate still can be assessed in this setting).
Clearly separate PGT-A cycles and donor egg treatments in all outcome data, with transparent labelling by age group.
Aim to develop reporting on cumulative live birth rate per cycle started. While we understand that cumulative live birth rate per cycle started is a more complex metric to present, it remains the internationally accepted gold standard – already adopted by SART/CDC (USA), CARTR+ (Canada), ANZARD (Australia/New Zealand), and endorsed by ICMART. These systems recognise that the patient journey begins with a cycle start, not with an embryo transfer, and that fair reporting must reflect the full scope of that journey.
These concerns are not new. For well over a decade, clinicians and academics have pointed out that current reporting frameworks – including the continued reliance on embryo-based metrics – allow for distortion, selective exclusion, and confusion. Multiple studies and professional commentaries, including from members of our own team, have outlined how such practices undermine the original goals of the HFE Act: to inform, protect, and empower patients. Yet despite these repeated calls, meaningful reform has lagged behind international best practices. With the current update to CaFC, the Authority has a rare opportunity to address long-standing weaknesses and restore confidence in how outcomes are reported and understood.

We also welcome clarity on the upcoming consultation process.

Will clinics, patients, and independent experts be able to contribute formally?
Will the consultation explicitly address the use and abuse of elective freeze-all cycles and multi-cycle commercial packages?
We note that the HFEA's 2025–2028 Strategic Plan includes strong commitments to transparent, patient-centred information and to reducing inequalities in treatment outcomes. We are concerned, however, that the current CaFC metrics – in particular the continued focus on embryo-based success rates – may not fully reflect those strategic priorities in practice. We hope the forthcoming consultation will be an opportunity to bridge this gap and bring CaFC into closer alignment with the Authority's vision.

We believe this is a critical moment. How the HFEA reports outcomes will influence not only patient choice, but also clinical practices and commercial models across the UK fertility sector. Inaccurate or overly simplified metrics carry real risk of harm and perpetuate inequity. Transparent, cycle-based reporting – underpinned by clear definitions and cumulative success data – is essential if CaFC is to become a truly trusted tool for patients.

We thank the Authority for recognising the weight of this responsibility and remain committed to supporting the development of a fairer, more clinically accurate system of reporting.

Professor Dusko ILIC, MD PhD
Professor of Stem Cell Science
King's College London Faculty of Life Sciences and Medicine
School of Life Course and Population Sciences
Department of Women and Children's Health
Person responsible for the HFEA clinical license 0102
Assisted Conception Unit, Guy's and St Thomas' NHS Foundation Trust

Dr Julia Kopeika, MD PhD, FRCOG
Consultant Gynaecologist
Head of Assisted Conception Unit, Guy's and St Thomas' NHS Foundation Trust
Lead For Fertility Preservation
Sub specialist in Reproductive Medicine and Surgery

Professor Yacoub Khalaf, MD, FRCOG
Professor of Reproductive Medicine and Surgery
King's College, London Consultant in Reproductive Medicine and Surgery
Guy's and St Thomas' NHS Foundation Trust Medical Director of the Assisted Conception Unit and Centre for PGD

Tarek El-Toukhy, MSc MD MRCOG
Consultant Gynaecologist
Senior Lecturer, King's College London
Subspecialist in Reproductive Medicine and Surgery
Assisted Conception Unit, Guy's and St Thomas' Hospital NHS Foundation Trust

Professor Caroline Mackie Ogilvie, BSc DPhil OBE
Guy's and St Thomas' NHS Foundation Trust

Professor Ying Cheong, MD, FRCOG
Professor of Reproductive Medicine
University of Southampton

Some of the issues discussed in this open letter will be explored at this year's PET Annual Conference, What Does Genomics Mean for Fertility Treatment?.