Is Microbiome Testing Worth It for IVF? What the HFEA Says

By the Zita West Nutrition Team. Last reviewed: November 2026.

If your clinic has offered a microbiome test before IVF, you may be wondering whether it is worth paying for. On 30 October 2026, The Times reported a warning to couples that costly "good bacteria" add-ons might not help.^[2] The guidance behind it comes from the Human Fertilisation and Embryology Authority (HFEA), the UK's fertility regulator, which in September 2026 rated the treatments offered after microbiome testing as grey.^[1]

This article sets out what the HFEA did and did not assess, what the wider research shows, and what both partners can sensibly do in the months before a cycle. It follows our recent look at the latest research on egg quality and IVF.

What the HFEA found

The HFEA treats microbiome testing as a treatment add-on: an optional extra offered on top of standard IVF, usually at extra cost. In fertility treatment, testing usually involves a sample from the vagina or the lining of the womb, and some clinics also offer gut microbiome testing.^[1]

If a test suggests an imbalance, patients may be advised to take antibiotics, probiotics, or both, before IVF. It is these follow-on treatments that the HFEA rated.^[1]

According to the HFEA's microbiome testing guidance, probiotics, probiotics with antibiotics, and antibiotics following microbiome testing are rated grey for improving the chance of having a baby for:

• most fertility patients;
• patients with recurrent implantation failure (RIF);
• patients with chronic endometritis, a long-term inflammation of the womb lining, where antibiotics with or without probiotics are also rated grey for reducing miscarriage.

The HFEA also notes that the full results of a large trial on chronic endometritis and recurrent miscarriage (the CERM trial) have not yet been published, so they were not included in its assessment.^[1]

What the HFEA did and did not assess

The HFEA reviewed whether treatments offered after microbiome testing improve fertility outcomes. It did not assess the accuracy or clinical usefulness of individual microbiome tests.^[1]

The HFEA says there is currently no agreed best way to carry out microbiome testing or interpret the results, meaning different laboratories may give the same patient different results and advise different treatments. It also says the results are unlikely to change how treatment is managed.^[1]

The regulator's wider point is that, for most patients, a routine cycle of proven fertility treatment is effective without add-ons. If you are paying privately, it suggests thinking about whether money would be better spent on further cycles.^[1] That is a separate question from the everyday steps you can take to prepare for IVF, which are about your general health rather than an add-on.

How the HFEA rating system works

The HFEA uses five ratings. Green means high quality evidence shows an add-on is effective. Yellow means the evidence is conflicting. Grey means the HFEA cannot rate effectiveness because there is not enough moderate or high quality evidence. Black means good evidence shows no effect. Red means potential safety concerns, or evidence that an add-on may reduce effectiveness.^[1]

None of the add-ons the HFEA has reviewed has been shown to increase the chance of a baby for most patients, and the regulator expects clinics to explain clearly what any add-on involves, how likely it is to help and what it costs.^[3]

What the evidence shows, according to the HFEA

• Most fertility patients: some studies suggested probiotics may increase the chance of having a baby, but they had limitations and included small numbers of patients. Results for antibiotics were inconsistent and, taken together, showed no benefit.
• Recurrent implantation failure: some studies suggested probiotics, alone or with antibiotics, may help, but the evidence came from small, low quality studies, with no clear improvement in ongoing pregnancy or miscarriage.
• Chronic endometritis: studies of antibiotics, with or without probiotics, generally found no clear improvement in the chance of having a baby or in reducing miscarriage.

Source: HFEA microbiome testing guidance.^[1]

What is the reproductive microbiome?

The microbiome is the community of bacteria, fungi and viruses living in and on the body. Many are a normal and important part of a healthy body.

In the vagina, a healthy microbiome is usually dominated by Lactobacillus species. Around 80% of women of reproductive age without symptoms have a vaginal microbiome dominated by one of four species: L. crispatus, L. gasseri, L. iners or L. jensenii.^[4] These bacteria produce lactic acid, keeping the environment acidic and less welcoming to unwanted organisms.

When Lactobacillus levels fall and other bacteria take over, this is called dysbiosis. Bacterial vaginosis (BV) is the most familiar example. You can read more in our guide to the vaginal microbiome.

The womb was once thought to be sterile. Research over the past decade suggests it has its own, much smaller microbiome, which is what endometrial tests look at.^[5]

Why researchers are interested

The link between Lactobacillus and IVF outcomes is not new. In a 2016 study of 35 women having IVF, those whose endometrial fluid was not Lactobacillus dominated had markedly lower implantation, pregnancy and live birth rates.^[5]

That study was small, and it was carried out by the company that went on to develop endometrial microbiome testing. It was an important starting point, but small early studies often show larger effects than later, bigger trials confirm.

For a closer look at the strains studied in relation to fertility, including L. crispatus, see research on Lactobacillus crispatus and fertility.

Microbiome tests explained

According to the HFEA, microbiome testing may be offered to patients with recurrent implantation failure or suspected chronic endometritis. Some clinics also offer it more generally before treatment, as part of what may be described as "fertility optimisation".^[1]

What are the EMMA and ALICE tests?

EMMA (Endometrial Microbiome Metagenomic Analysis) looks at the balance of bacteria in a sample of the womb lining, including how much of it is Lactobacillus. ALICE (Analysis of Infectious Chronic Endometritis) looks for bacteria linked with chronic endometritis.

These tests may be offered by some clinics, but the HFEA does not assess individual test brands and has not concluded that treatment based on microbiome testing improves live birth rates.^[1]

Clinics sometimes offer endometrial receptivity testing at the same time. The HFEA points out that this is a separate test, not a microbiome test.^[1] To understand how timing and the womb lining fit together, see our guide to endometrial receptivity testing.

Is microbiome testing safe?

The HFEA describes vaginal and endometrial testing as generally low risk. A vaginal swab can cause mild discomfort or light spotting. Taking a sample from the womb lining can cause discomfort, cramping or light bleeding, and carries a small risk of infection.^[1]

Typical UK costs to ask about

As reported by The Times, UK patients may be offered:^[2]

• Home vaginal microbiome test kits: around £60 to £150.
• Clinic tests of the microbiome: around £200.
• Advanced testing of the womb and reproductive tract: up to around £1,000.

Prices vary by clinic and may not include consultations, sampling, medication or repeat testing. Ask for the full cost before deciding.

Questions to ask your clinic

• What would the result change about my treatment plan?
• What treatment would you recommend if the result is abnormal, and what are its side effects?
• What is the total cost, including any repeat testing or follow-up treatment?
• What does the HFEA rating say about this add-on for someone in my situation?

Probiotics, antibiotics and IVF: the wider research

Beyond the HFEA review, the most studied area is vaginal dysbiosis and IVF. A 2021 review of 17 studies and 3,543 IVF patients found that vaginal dysbiosis was associated with a higher rate of early pregnancy loss and, where it was diagnosed using modern molecular methods, a lower clinical pregnancy rate.^[4]

A larger review published in 2024, covering 25 studies and 6,835 IVF patients, found vaginal dysbiosis in around one in five patients. It was linked with clinical pregnancy and early pregnancy loss, but not with live birth rates, which the authors described as difficult to explain.^[6]

In other words, the association between a disrupted microbiome and IVF outcomes is real enough to keep researchers interested. What is missing is good quality evidence that testing and then treating it improves the chance of a baby, which is the question the HFEA looked at. For more on probiotics specifically, see probiotics and fertility outcomes.

The HFEA also flags safety points. Unnecessary or repeated antibiotics may contribute to antibiotic resistance and can cause side effects such as feeling sick or diarrhoea. Probiotics may cause minor side effects such as bloating.^[1]

What a grey rating means for your decision

Regulators such as the HFEA and NICE have a specific job: to judge whether a treatment has been shown to improve outcomes. That is an important safeguard for couples making expensive decisions.

It is not their job to give a fuller picture of where the research is heading, or what a couple might reasonably do in the meantime. That is where a balanced view helps.

Katie Rollings, chief executive and founder of the patient charity Fertility Action, told The Times that a grey rating reflects a lack of evidence, which "doesn't mean there is no evidence".^[2] She added that building a high quality evidence base could take ten to 15 years, which is frustrating for patients who need to make decisions now.

So it helps to separate two questions:

• Should I pay for microbiome testing and follow-on treatment as an IVF add-on? The evidence does not yet show it improves the chance of a baby. That is a decision to make carefully with your clinic, using the HFEA ratings.
• Is it worth looking after my microbiome as part of preparing for IVF? Supporting gut and vaginal health through diet, lifestyle and, for some people, a probiotic is part of general preparation. It is not a treatment, and no single thing can guarantee an outcome.

What about the male partner?

The HFEA guidance covers vaginal, endometrial and gut microbiome testing. It does not assess the male microbiome, so nothing in this section is an HFEA finding or recommendation.^[1] Some clinics do offer microbiome testing for male partners, as The Times reported.^[2]

Semen has its own microbiome. Researchers think its bacteria probably come from several places, including the gut, urinary tract and prostate, and most studies so far have been cross-sectional, so cause and effect are unclear.^[7] A systematic review concluded that the effect of the seminal microbiome on sperm quality is still unclear, because research is limited and results are inconsistent.^[8]

Sperm take around three months to develop, so if you are making general diet and lifestyle changes before treatment, it makes sense for both partners to start at the same time. Read more about sperm health, gut health and sperm, and male fertility and probiotics research.

Recurrent implantation failure and chronic endometritis

These are the two groups the HFEA looked at specifically, and in both cases the follow-on treatments were still rated grey.^[1] If you have had several transfers that did not implant, or have been told you may have chronic endometritis, it is worth a detailed conversation with your clinic about all the factors that could be involved, of which the microbiome is only one.

For practical guidance, see our article on uterine lining health.

Who might consider talking to a specialist

This is general advice rather than part of the HFEA review. Endometriosis, for example, was not one of the patient groups the HFEA assessed.

• Anyone with recurrent BV or symptoms such as unusual discharge, odour or discomfort, which should be checked by a GP or sexual health clinic.
• Anyone who has had several embryo transfers that did not implant.
• Anyone with endometriosis or a history of pelvic infection.
• Anyone offered antibiotics before embryo transfer who wants to understand why.

What you can do now

Whatever you decide about testing, the months before a cycle are a window both partners can use well. Eggs mature over roughly 90 days and sperm take around 74 days to develop, so starting about three months ahead gives nutrition and lifestyle changes time to matter.

• Eat for your gut: a varied diet with plenty of vegetables, wholegrains, legumes and fermented foods supports a diverse gut microbiome.
• Be thoughtful about antibiotics: take them when they are clinically needed, and ask questions if they are offered as a precaution.
• Look after vaginal health: avoid douching and scented washes, which can disrupt the natural balance.
• Consider a probiotic for both partners: as part of a wider preconception routine, not as a replacement for medical advice or treatment.

Femceive

A daily probiotic for women containing three Lactobacillus strains, L. crispatus BPL209, L. rhamnosus BPL205 and L. plantarum BPL207, to support vaginal and gut health while preparing for pregnancy. One capsule a day, as a 34 or 102 day course.

Shop Femceive

Menceive

A daily probiotic designed for men, to support gut health as part of a preconception routine for the male partner. One capsule a day, as a 21 or 63 day course.

Shop Menceive

The microbiome does not change overnight. Our guide on how long it takes to support your microbiome explains why starting early helps.

Speak to your fertility clinic before starting any supplement during active treatment, and always tell them what you are taking.

Not sure where to start?

At Zita West, we include a probiotic in the foundations we suggest for both partners preparing for IVF, alongside nutrients such as folate, vitamin D and omega-3. We start with the couple, their stage and their history, not with a product.

You can browse our IVF supplements, or book a free 1:1 product consultation with our nutrition team for personalised guidance on what is most relevant for you both.

Frequently asked questions

Is microbiome testing worth it for IVF?

The HFEA rates the treatments offered after microbiome testing as grey, meaning there is not enough moderate or high quality evidence to show they improve the chance of having a baby. If your clinic offers testing, ask what the result would change, what treatment may follow and what the total cost would be.

What did the HFEA say about microbiome testing?

The HFEA rated probiotics, antibiotics, or both, given after microbiome testing as grey for improving the chance of having a baby. This applies to most fertility patients, patients with recurrent implantation failure and patients with chronic endometritis. The HFEA did not assess the tests themselves.

What does a grey HFEA rating mean?

Grey means the HFEA cannot rate whether an add-on is effective because there is not enough moderate or high quality evidence. It is different from black, which means good evidence shows an add-on has no effect. A grey rating means the question is still open.

What are the EMMA and ALICE tests?

EMMA analyses the bacteria in a sample of the womb lining, including how much is Lactobacillus. ALICE looks for bacteria associated with chronic endometritis. The HFEA does not assess individual test brands and has not concluded that treatment based on microbiome testing improves live birth rates.

How much does a vaginal microbiome test cost in the UK?

The Times reported that home vaginal microbiome kits cost around £60 to £150, clinic tests around £200, and advanced testing of the womb and reproductive tract up to around £1,000. Prices vary by clinic and may not include consultations, sampling, medication or repeat testing.

Should I take probiotics before IVF?

A probiotic can be a sensible part of a wider preconception routine for both partners, alongside a varied diet and healthy lifestyle. No supplement can guarantee an IVF outcome, and you should tell your clinic about anything you are taking during treatment.

Can BV affect fertility?

Bacterial vaginosis and other forms of vaginal dysbiosis have been associated with lower clinical pregnancy rates and higher early pregnancy loss in IVF studies, although an effect on live birth rates has not been shown. If you have symptoms of BV, see your GP or a sexual health clinic.

Does the male partner's microbiome matter for IVF?

The HFEA guidance does not cover the male microbiome. Research into the semen microbiome is at an early stage, and its effect on sperm quality is still unclear.

How does Zita West approach probiotics for fertility?

Zita West includes a probiotic in the foundations suggested for both partners preparing for IVF, as part of a wider nutrition routine. Femceive is designed for women and Menceive for men, and our nutrition team can advise on what fits your stage and history.

References

1. Microbiome testing (Human Fertilisation and Embryology Authority, published 18 September 2026) ↩
2. Marsh B. IVF couples warned costly 'good bacteria' add-ons might not help (The Times, 30 October 2026) ↩
3. HFEA statement on new study into fertility treatment add-ons (Human Fertilisation and Embryology Authority, June 2026) ↩
4. Skafte-Holm A, et al. The association between vaginal dysbiosis and reproductive outcomes in sub-fertile women undergoing IVF treatment: a systematic PRISMA review and meta-analysis (Pathogens, 2021) ↩
5. Moreno I, et al. Evidence that the endometrial microbiota has an effect on implantation success or failure (American Journal of Obstetrics and Gynecology, 2016) ↩
6. Maksimovic Celicanin M, et al. Vaginal dysbiosis: the association with reproductive outcomes in IVF patients, a systematic review and meta-analysis (Current Opinion in Obstetrics and Gynecology, 2024) ↩
7. Osadchiy V, et al. The seminal microbiome and male factor infertility (Current Sexual Health Reports, PMC) ↩
8. Brandão P, et al. Seminal and testicular microbiome and male fertility: a systematic review (Porto Biomedical Journal, 2021) ↩

Related guides

• Fertility and the Vaginal Microbiome: The Research Behind Femceive
• Probiotics and Male Fertility: The Research Behind Menceive
• The Vaginal Microbiome: All You Need to Know
• Preparing for IVF: Nutrition, Lifestyle, and Supplements
• Egg Quality and Age: Why It Declines, and What New Research Means for IVF

Microbiome testing is a genuinely interesting area of fertility research, but the evidence is not yet strong enough to show that treatment based on it improves the chance of a baby. Whatever you decide about testing, the months before treatment remain the window you can make the most of, for both partners.

Medical disclaimer: this article is for general information and does not replace personal advice from a GP, midwife, fertility clinic or qualified healthcare practitioner, especially if you are pregnant, breastfeeding, taking medication or undergoing fertility treatment.