Endometrial Receptivity: 5 reasons why you may be experiencing Implantation Failure.

When it comes to fertility, conception is only a part of this delicately orchestrated process. The successful implantation of the embryo into a receptive endometrial lining is just as important, and implantation failure is one of the biggest causes of recurrent chemical pregnancies and pregnancy loss.

With fertility education, the primary focus is usually on the health of the egg and the sperm; however, without a receptive endometrial lining, even a perfect embryo cannot implant into the uterus, and the pregnancy is unlikely to progress.

Recurrent chemical pregnancies, which are early pregnancy losses, usually as early as 4–5 weeks, are very common and account for 50-75% of pregnancy loss. Chromosomal abnormalities account for 70–75 % of these, but many are unexplained, especially recurrent ones, as you would be unlucky to have a chromosomal issue every time one occurred. A huge number of these unexplained early pregnancy losses are because of implantation failure, which is the inability of the embryo to implant successfully into the uterine lining, resulting in early pregnancy loss. According to recent data `the leading single cause of pregnancy failure is embryo implantation error, which can occur up to a rate of 78% in humans’ (1). 

This article raises awareness of some of the common factors that may make an endometrial lining unreceptive to the developing embryo. The process of implantation is such a delicate orchestra involving hormones, the immune system, our endometrial microbiome, and nutrient cofactors that it is amazing that pregnancies can happen successfully in the first place; they truly are a miracle.

What are the most common causes of implantation failure?

According to recent research, the most common reasons for unexplained recurrent implantation failure that are not chromosomal reasons or structural reasons (e.g. endometriosis, fibroids) are:

●       Low progesterone

●       Autoimmune thyroid issues

●       Chronic inflammation

●       Endometrial dysbiosis

●       Nutritional deficiencies 

I am going to explore each of these areas in more detail. It is important to note that our diet, lifestyle, and environment influence most of these issues, and we can take many positive daily actions to improve and optimize our health in each of these areas.   

Low progesterone

We all know that the hormone progesterone is dominant from ovulation until menstruation and is important for maintaining a pregnancy. However, did you know that unless you have adequate levels of progesterone around the implantation window, there is a high risk that implantation will fail?  

Progesterone is an anti-inflammatory hormone and, according to studies, it induces immune tolerance at implantation as well as during early pregnancy. Implantation usually occurs at the peak of progesterone secretion during the luteal phase, which is normally around 7 -10 days after ovulation, although it can vary between individuals and even from month to month in the same person.

The preparation of a receptive endometrial lining is influenced by the hormones estrogen and progesterone. Estrogen plays a primary role in the ‘proliferation,secretion and remodelling’ (2) of the endometrial lining in the preovulatory phase and induces an increase in the expression of progesterone receptors ready for progesterone in the post-ovulatory phase. It is important that estrogen is in a healthy balance as excess estrogen can also have a detrimental effect on endometrial receptivity.  

After ovulation has occurred, progesterone induces major cellular changes within the endometrium that are essential for creating a receptive environment for the embryo, which will be important for maintaining early pregnancy. In addition to this, progesterone plays a critical role in inducing immune tolerance in early pregnancy, modulating the maternal immune response.

Immune tolerance during implantation is a critical step of reproduction that plays a make-or-break role in whether the pregnancy will continue. Immune tolerance refers to the maternal immune system’s ability to accept and support a semi-allogeneic embryo (carrying both maternal and paternal antigens) during pregnancy, despite its natural inclination to reject any foreign tissues. ‘On the one hand, the maternal immune system is evolutionarily primed to recognise and eliminate non-self elements: on the other, during pregnancy it must tolerate and support a semi-allogeneic entity (the embryo) that carries both maternal and paternal antigen.’ (3)

For implantation to be successful, it requires a tightly regulated interplay between immune tolerance mechanisms and controlled inflammatory responses. If dysregulation of this delicate balance occurs, then implantation will fail. Progesterone plays a huge part in this process of immune tolerance as it ‘drives the polarization of circulating and tissue resident immune cells towards an anti-inflammatory phenotype to promote a tolerogenic microenvironment, a process that involves downregulating the release of pro-inflammatory mediators.’ (4) 

So, if progesterone has the biggest influence on whether an embryo is rejected or not, maintaining progesterone levels is of the utmost importance, especially in women over the age of 35, where progesterone levels are on a natural decline. If you are undergoing IVF, you can at least be assured that your progesterone levels will be monitored and you may be prescribed a progesterone suppository if needed. But what if you are not undergoing IVF? How do you make sure you have adequate progesterone levels?

It is not always possible or realistic to test your hormones every month, so looking out for signs and symptoms of low progesterone, or a luteal phase defect is important. In the first instance food and nutrients can support progesterone levels and may be all you need, depending on your age and any chronic conditions you have.

Here are some of the common symptoms of low progesterone:

●     Premenstrual syndrome (PMS)

●     Irregular periods

●     Shorter cycles of around 24 days

●     Headaches

●     Mood changes, depression, or anxiety

●     Hot flashes

●     Bloating, weight gain

●     Swollen and tender breasts

●     Sleep issues

●     Infertility

Fortunately, there are many diet and lifestyle suggestions that we can adopt to help support healthy progesterone levels. These include:

Add 1 tablespoon of freshly ground linseed to smoothies or breakfast cereal. Linseed (otherwise known as flaxseed) contains lignans, a phytochemical that can help to balance estrogen and progesterone.

You may also wish to do seed cycling, which is eating freshly ground seeds at certain times in your cycle for the effect they have on hormone production. According to seed cycling experts, eating raw ground sunflower and sesame seeds on days 15–28 of your cycle can increase progesterone levels.

Eat hormone-building foods - a healthy balance of protein, healthy fats and complex carbohydrates from vegetables and grains. Low-carbohydrate diets after ovulation may negatively impact progesterone.

Eating broccoli or broccoli sprouts regularly to help detoxify excess estrogen.

Eat foods rich in vitamin B6 as it is very supportive if you have a luteal phase defect as it helps to increase progesterone levels. Foods that are rich in vitamin B6 are chicken, pork, eggs, banana, liver, salmon, sweetcorn, Brussel sprouts, spinach, capsicum, garlic, cauliflower, celery, cabbage, broccoli, brewer’s yeast, and wholegrain cereals.

Reducing stress - as high cortisol levels shuts down the production of progesterone in the adrenal glands.

Prioritise sleep, try to be in bed by 10.00pm at least 3 days a week

Supplementing with a good multivitamin that contains a full spectrum of minerals with activated B vitamins

Taking a good source of omega-3 and evening primrose oil

Work with an experienced practitioner to see if you would benefit from taking the herb vitex (also called chaste tree) as it is well known for its hormone-regulating properties, including the ability to increase progesterone levels and lengthen the luteal phase.

Autoimmune thyroid issues

Thyroid autoimmunity is one of the most common autoimmune disorders affecting women during childbearing years, and the prevalence is especially high in women experiencing unexplained infertility and recurrent pregnancy loss. Autoimmune thyroid affects around 5 - 15% of women, but the prevalence is 14.5% - 22.8% in women with unexplained infertility and 17.57% in recurrent pregnancy loss.

A characteristic of autoimmune thyroid conditions is the presence of thyroid antibodies in the blood, which can be tested with a blood test. Thyroid antibodies are produced by the immune system and mistakenly target healthy thyroid tissue, which may lead to inflammation, thyroid tissue damage and dysfunctional thyroid function. Normally antibodies form in the blood to protect the body from foreign invaders such as viruses and bacteria; however, with thyroid autoimmunity, the immune system goes rogue and starts to attack the body’s own thyroid tissue, mistaking it for a foreign invader.

There are two main types of antibodies: thyroid peroxidase antibodies (TPOAb) which are most commonly associated with Hashimoto’s Thyroiditis and thyroid-stimulating hormone receptor antibodies (TRAb) which are characteristic of Grave’s disease. Thyroglobulin antibodies (TgAb) are also usually tested and are another indicator of Hashimoto’s thyroiditis.   

The presence of thyroid antibodies in the blood, even with 'normal’ thyroid function, can affect endometrial receptivity by disrupting immune homeostasis within the endometrium during the implantation window. Women with elevated thyroid antibodies tend to have dysfunctional T cells and more NK cells in the blood and uterus.

The important point to note here is that autoimmune thyroid disease, such as (Hashimoto's and Graves' disease) can significantly impact endometrial receptivity even in women who have normal thyroid hormone levels. Many women do not realise they have autoimmune thyroid as the only way this would be tested is to have a full thyroid panel to test for the presence of the thyroid antibodies TPOAb, TgAb and TRAb. If any of these antibodies are detected (even if they are not particularly elevated), it means that there is an immune attack on the thyroid gland going on, which disrupts the body's normal immune balance. What many people do not realise is an immune attack on the thyroid may still be going on even with normal thyroid hormone levels such as TSH and T4, which are the normal hormones tested by your GP. So, if your GP only does the basic thyroid testing and doesn’t test thyroid antibodies, you will never know that this is going on. Even low levels of thyroid antibodies can trigger an immune imbalance, and if not addressed, could develop into full-blown thyroid disease down the track. 'Approximately 79.3% of Hashimoto’s thyroiditis patients display an euthyroid (normal) state at diagnosis and may retain normal thyroid function for many years.’ (5)

So, the point is your GP may not know that there is a huge connection between thyroid antibodies and unexplained infertility and recurrent pregnancy loss so may not think to order these tests, just thyroid-stimulating hormone (TSH) which is likely to be within the normal range. You may then wish to push for your GP to test for thyroid antibodies, or ask a practitioner like myself to order a full thyroid panel for you. It is definitely something that needs ruling out, even if you don’t feel like you have a thyroid problem. 

How do thyroid antibodies affect endometrial receptivity even with normal thyroid function? 

According to a study, even with normal thyroid function `thyroid autoimmunity, with rising serum TPOAb and TgAb levels, is associated with repeated implantation failure.’ (6) 

It has also been shown that thyroid autoimmunity can directly impair endometrial implantation by altering the morphology and expression of receptivity markers in the endometrium. Some of the ways it does this are by:

1. Reducing the number of pinopodes, which are tiny, finger-like projections that develop on the surface of the endometrial cells during the window of implantation and play a role in embryo adhesion.`Many patients who have infertility due to implantation defects fail to produce pinpodes’ (7)

2. Altered or abnormal expression of receptivity markers such as estrogen receptor/alpha (ERa), integrin/beta3, leukemia inhibitory factor (LIF) and cell adhesion molecule-1 (ICAM-1)

   
   

Thyroid autoimmunity, even with normal thyroid function, can also disrupt the delicate immune balance within the endometrium, which is critical for implantation to be successful. It can lead to significant changes in the proportion of the immune cells in the endometrium. RNA sequencing has shown that people with autoimmune thyroid have increased proportions of T CD4+, cNK, ILC3 and T CD8 + cytotoxic cells along with a decrease in CD366 _ uNK1 cells and abnormal expression of GNLY and chemokines. Of note is that CD366 + uNk cells are beneficial to pregnancy immuno- tolerance and have been found to be decreased in women with autoimmune thyroid disease.

What does this mean? It means that there is an imbalance of immune cells, natural killer cells, and inflammatory cytokines in the endometrium and at the maternal-fetal interface, which will create an unfavourable environment for implantation as the embryo will probably be rejected.

This is why having your thyroid antibodies tested is so critical if you are experiencing infertility or recurring pregnancy loss, even if your GP has tested your thyroid and has confirmed it is normal.

Reference ranges for thyroid antibodies

The standard reference range for both TPOAb and TgAb thyroid antibodies is less than 35 IU/mL. So, if you have detectable antibodies of say 32 IU/mL for TPO, you are considered normal, but this is in fact showing that there is an autoimmune attack going on in which the immune system is attacking the thyroid gland. I see this so many times in my clinic, where clients have borderline thyroid antibody levels and are told they are normal.  In my opinion, if you are really struggling with unexplained infertility and recurrent pregnancy loss and do have detectable thyroid antibodies (even though they are not especially elevated), you should act like you have thyroid autoimmunity in terms of your diet and lifestyle.

The optimal reference range for both thyroid antibodies is less than 2 IU/mL. If your test results show that your antibodies are higher than this, it is important to look at nutritional or supplemental support to help lower your thyroid antibodies over time and increase your sense of wellbeing.

How to lower thyroid antibodies naturally

The approach to reducing antibodies is not to treat the thyroid as such,  but to focus on modulating the immune system, which hopefully over time will reduce immune system overactivity and restore immune system homeostasis.

The health of the gut plays an important role in immune system modulation as intestinal permeability (or leaky gut as it is overwise known), is often the root cause of autoimmunity. When the intestinal barrier is compromised or `leaky’ it allows undigested proteins (e.g. gluten and dairy), bacteria, toxins and other substances to enter the bloodstream. Circulating immune cells in the blood identify these as foreign invaders, and an immune response is triggered which leads to antibody production.

Treatment approaches that focus on restoring the gut microbiome with nourishing food and targeted probiotic strains are important as well as food and nutrients that heal and seal the intestinal lining. This will help to address the root cause of the immune dysregulation.

Identifying and removing food intolerances (especially gluten) can also help to calm down an overactive immune system. I will expand on the gluten-free diet as an important approach shortly.

These are the evidence-based natural treatments that have been shown in studies to help to reduce thyroid antibodies over time:

Vitamin D

As an important immunomodulator, vitamin D plays a significant role in reducing the risk of autoimmune diseases. In a 2023 study, vitamin D has a significant impact on reducing TPOAb and TGAb antibodies in patients with Hashimoto’s, and it also improved thyroid function by decreasing TSH levels and increasing T3 levels (8)

The recommended daily dose of vitamin D3 for those trying to conceive is around 2,000IU per day (preferably with K2 as they work as a team for bone health), although testing is advisable as you may need more than this.

Selenium

The results of various studies have indicated that selenium supplementation, typically at doses of 150-200 mcg a day, leads to a reduction of TPOAb antibody levels in patients with autoimmune thyroiditis. Selenium also helps to improve thyroid function as it is involved in the conversion of the inactive thyroid hormone T4 to the active thyroid hormone T3. It is important not to exceed 200mcg of selenium a day (in all supplements) unless under the guidance of a qualified practitioner as it can be toxic in very high levels.

Gluten-free diet

One of my core recommendations as a fertility nutritionist is to adopt a gluten-free diet while you are trying to conceive if you are experiencing unexplained infertility and recurrent pregnancy loss. This is whether you are formally diagnosed with coeliac disease or not. In my experience, going gluten-free has been the missing link that has helped many of my clients improve their gut health, bring down inflammation and reduce thyroid antibodies, all factors that significantly improve their chances.  

There have been several studies over the last 10 years linking gluten to infertility and recurrent miscarriage. This is because gluten is inflammatory for many people and can cause damage to the lining of the small intestine, which can lead to the development of coeliac disease (which can often go undiagnosed) as well as several other autoimmune issues that could contribute to infertility. Some studies have also suggested that adopting a gluten-free diet can have a positive influence on lowering thyroid antibody levels.

Polyphenol rich diet

Foods rich in polyphenols such as red wine, dark chocolate, tea, coffee, and many coloured fruits and vegetables have anti-inflammatory and anti-antioxidant properties that can help to protect our cells and tissues against oxidative stress, which can impair the function of the thyroid and lead to autoimmunity. Berries, grapes, plums, oranges, kiwifruit, pomegranate, coffee, green tea, black tea, red wine, hazelnuts, almonds, walnuts, spinach, broccoli, red onion, asparagus, are all rich in polyphenols which also have prebiotic properties so are also beneficial for gut health.

Black cumin seed oil (Nigella Sativa)

The antioxidant, anti-inflammatory and immunomodulatory properties of black cumin seed oil can also be beneficial for reducing thyroid antibodies. Clinical trials have shown promising results, which include a significant reduction in TPOAb antibodies (one study reported a nearly 50% decrease) and a positive improvement in thyroid function.  

Other autoimmune diseases

I have focused on autoimmune thyroiditis in this blog as it is the most prevalent autoimmune condition in women during childbearing years and it is a common issue I am seeing in my clinic. If you have a different autoimmune condition (e.g. Coeliac disease, lupus, Rheumatoid arthritis, etc) then the approach would be similar as you are essentially still dealing with the same root cause and immune dysregulation, but the location of the immune attack that is different. Supporting the gut, a gluten-free diet, polyphenol-rich foods, vitamin D, selenium and an anti-inflammatory approach will still be important.

Silent low-grade inflammation

Chronic inflammation may also contribute to implantation failure by promoting an immune system imbalance with a pattern of elevated Th17 immune cells and decreased T regulatory cells. Researchers estimate that silent, low-grade inflammation can cause up to 50% of cases of unexplained infertility. This is a big topic in itself in which I wrote a blog on a couple of years ago. Check out: Could silent low-grade inflammation be the cause of your unexplained infertility?

Endometrial microbiome dysbiosis

Recent research has moved away from the perception of the uterus as a sterile environment to more of a dynamic microbial ecosystem that is influenced by the health of the gut as well as the vagina. There is now a recognised connection between the gut microbiome, vaginal microbiome and endometrial health known as the gut-vaginal - endometrial axis. Recurrent pregnancy loss, implantation failure, and conditions such as endometriosis and PCOS are all linked to an imbalance in the endometrial microbiome.

A healthy endometrial microbiome is important for maintaining immune balance and endometrial lining integrity, which is critical for preparing the uterus for implantation. Recent research has found that a healthy endometrium is generally lactobacillus dominant, accounting for approximately 80-90% of the microbiome population. This lactobacillus dominance is associated with higher rates of implantation success and improved reproductive outcomes, including IVF.

In particular, the dominance of the probiotic strain Lactobacillus Crispatus is strongly correlated with positive reproductive outcomes and higher pregnancy rates. ‘Women with a live birth compared to those without had significantly higher Lactobacillus Crispatus relative abundance’ (9)

This is all pretty exciting new research that has only really been published in 2023, so it wasn’t on my radar when I was studying all things fertility before I conceived my daughter naturally in 2019 after 10 years of unexplained secondary infertility and recurrent pregnancy loss. The good news is that there are many female urogenital probiotics available these days that contain variations of the strain Lactobacillus Crispatus. They mainly target the vaginal microbiome and are useful for the prevention and treatment of urinary tract infections, bacterial vaginosis and thrush. As there is a proven link between the health of the vaginal microbiome and the endometrium (as bacterial strains are thought to travel up the urogenital tract) supporting the vaginal microbiome with lactobacillus crispatus as a probiotic supplement seems a beneficial thing to do in the preconception period.  

What are the specific benefits of Lactobacillus Crispatus?

It produces both L- and D-lactic acid, which helps to maintain a vaginal ph below 4. This acidic environment is beneficial as it inhibits the growth of pathogenic bacteria.

It produces hydrogen peroxide (H202) which has antimicrobial action, keeping pathogenic bacteria under control, preventing the translocation of bacteria from the lower urogenital tract to the endometrium, which could disrupt the delicate implantation process.

It plays an important role in immune system modulation in the endometrium, helping to establish an environment that is conducive to the successful implantation of the embryo.  It helps the maternal immune system to develop tolerance towards the embryo, reducing the risk of immune rejection, which can lead to implantation failure.

It helps to lower inflammation by elevating levels of anti-inflammatory cytokines such as interleukin 10 (IL-10) and insulin-like growth factor 1 (IGF-1)

It is able to have a positive impact on endometrial tissue by increasing endometrial thickness and promoting vascularization, which is important for enhancing endometrial receptivity. 

It modulates host gene expression and activates key cellular signalling pathways that are involved in tissue remodelling, vascularization and embryo attachment.

So what is clear from all the research from 2023 onwards is that a lactobacillus-dominant endometrial microbiome (which includes the presence of lactobacillus crispatus) during implantation is likely to increase the chances of a successful pregnancy, whether natural or through IVF.

Interestingly, in a 2023 study, women with primary infertility compared to secondary infertility, had significantly higher lactobacillus crispatus dominance than women with secondary infertility. This suggests that secondary infertility is associated more with endometrial dysbiosis than with primary infertility (10). The hormone and metabolic changes and challenges to a woman postpartum can contribute to endometrial dysbiosis so addressing the gut microbiome in cases of secondary infertility is essential.

Improving gut health is often the missing link in many cases of infertility and recurrent pregnancy loss, and I have seen this myself so many times in my clinic, especially with my clients who have thyroid issues or hormone imbalances. If you are not currently focused on optimising your gut health as part of your preconception care plan, then now is the time to start. Improving your gut health will also improve the health of your vaginal and endometrial microbiome as they are connected. For ideas on how to support your gut health, check out my previous blog post: Is your gut health affecting your fertility?

Nutritional deficiencies

As we have discussed previously, endometrial receptivity, which is the uterine lining's ability to allow for embryo implantation, is a crucial factor in a successful pregnancy. Implantation failure is a common occurrence both in natural conception and in assisted reproduction and is a key factor in very early pregnancy loss.

Nutritional deficiencies can significantly affect this process, as many nutrients influence a healthy hormonal balance, thyroid function, uterine health, and overall cellular function.

Here are some of the key nutritional deficiencies that can affect endometrial receptivity:

Vitamin D

A deficiency in vitamin D reduces endometrial receptivity and IVF success rates and plays an important role in implantation. It is important because it influences the expression of genes crucial for implantation, which can influence the structure and thickness of the endometrium. It also modulates immune responses vital for embryo implantation and pregnancy maintenance. Vitamin D supplementation is critical if you face reproductive challenges or are over the age of 40.

Folate

As folate is essential for gene expression,DNA synthesis and repair, folate deficiency can impair the formation of the uterine lining, directly affecting implantation. Folate supplementation is essential for women trying to conceive, and higher doses may be required if you have a MTHFR mutation. For more information on this, check out my blog post on folate vs folic acid 

Vitamin E

A deficiency in vitamin E may impair blood flow to the uterus, reducing endometrial receptivity. Studies have shown that vitamin E supplementation may improve endometrial receptivity by increasing endometrial thickness and blood flow, thereby enhancing implantation rates. Vitamin E is a fat-soluble antioxidant that helps to neutralise free radical damage that may negatively affect endometrial tissues. 

Vitamin B6

A deficiency in vitamin B6 may affect hormone balance and the length of the luteal phase, which may impact on implantation. Vitamin B6 supports progesterone levels, and we know how crucial progesterone is for preparing the endometrial lining for implantation. Vitamin B6 may cause nerve damage at high levels, so it is best not to self-prescribe vitamin B6 and work with a practitioner. In the very least, it is advisable to optimise vitamin B6 from food sources and your prenatal multivitamin. See earlier in this blog for food sources.

Vitamin B12

A deficiency in vitamin B12 can affect methylation and lead to elevated homocysteine levels, which can impair blood flow to the uterus, affect the thickness of the endometrial lining, and reduce implantation success. Optimal vitamin B12 levels are associated with improved fertility outcomes. It is important for vitamin B12 levels to be checked as part of a preconception screening as low B12 levels can be a factor in recurrent chemical pregnancies. If B12 levels are less than optimal (500 pg/mL or above) then supplementation will be beneficial. 

Iron

Iron deficiency can affect endometrial receptivity because of a lack of oxygen and blood flow to the uterus, potentially decreasing the chances of successful embryo implantation. Iron deficiency can also impair the expression of genes and proteins involved in endometrial receptivity, which can increase the chances of implantation failure. A chemokine known as Fractalkine (FKN) plays an important role by regulating iron metabolism in the endometrium and influencing the expression of genes related to iron uptake, release and storage. Optimising iron with food choices (e.g. beef, lamb, liver) and testing for iron deficiency is an important part of preconception screening.

Zinc

The mineral zinc is crucial for overall reproductive health and can support endometrial function. Zinc is essential for DNA synthesis, cell division, gene expression and a healthy balance of hormones, which all contribute to the preparation of the endometrial lining for implantation.

Calcium

Adequate calcium levels are important for successful embryo implantation because calcium deposits at the implantation site and influences endometrial receptivity. Calcium signalling plays a crucial role in many of the stages of implantation. This includes blastocyst-endometrium adhesion and the expression of genes involved in the implantation process. If calcium signalling is disrupted, then there is a risk of implantation failure. If need to be on a dairy-free diet (not recommended for fertility unless you have a food allergy), you may not be optimising calcium levels to support implantation, and will need to eat plenty of non-dairy food sources such as sesame seeds, tofu, almonds, kale canned salmon or sardines with bones, figs, orange or calcium enriched milk alternatives.

Omega 3

Because of their anti-inflammatory properties, omega-3 essential fatty acids can help create an optimal uterine environment for embryo implantation, improve uterine blood flow and influence the thickness of the endometrium. A deficiency can promote chronic inflammation, which can impair implantation. Omega-3 intake can be optimised through diet; however, supplementing with a good quality omega-3 such as cod liver oil can be beneficial as most people do not get enough omega-3 from dietary sources. Good sources of omega-3 are fatty fish (salmon, tuna, sardines), as well as walnuts, flaxseeds, chia seeds and hemp seeds; both the seeds and the oil are recommended.  

A comprehensive and balanced nutritional approach is fundamental for supporting endometrial receptivity and improving the chances of successful embryo implantation.

Next steps

So if you are experiencing recurrent pregnancy loss and/or recurrent implantation failure it is important to work with a qualified fertility practitioner who will take a holistic approach to optimising implantation and will work with you to investigate the root cause of why you are having issues. This should include:

• Testing and optimising progesterone levels

• Testing for thyroid antibodies and a plan to reduce these if elevated

• Support immune system function

• Supporting gut health and optimising lactobacillus dominance within the endometrial microbiome

• Optimising the nutrients that support successful implantation
  

If you need further assistance, feel free to contact me by phone or email or take advantage of my FREE 15-minute discovery session. You can book this online by clicking here . This is a great chance for us to have a chat about your situation and how I can help you. 

References

1. Zhangbi Wi et al. Hashimoto's Thyroiditis impairs embryo implantation by compromising endometrial morphology and receptivity markers in euthyroid mice.  Reproductive Biology and Endocrinology, 2019, 17:94

   
   

2. Morgan J,  Embryo Implantation and the Maternal Immune System: the tolerance-defence paradox. European Fertility Society, May 28 2025.

   
   

3. Motomura k et al. The effects of progesterone on immune cellular function at the maternal-fetal interface and in maternal circulation. The Journal of Steroid Biochemistry and Molecular biology, Vol 229, May 2023, 106254

   
   

4. Zhangbi Wi et al. Hashimoto's Thyroiditis impairs embryo implantation by compromising endometrial morphology and receptivity markers in euthyroid mice.  Reproductive Biology and Endocrinology, 2019, 17:94

   
   

5. Zhangbi Wi et al. Hashimoto's Thyroiditis impairs embryo implantation by compromising endometrial morphology and receptivity markers in euthyroid mice.  Reproductive Biology and Endocrinology, 2019, 17:94

   
   

6. Zhangbi Wi et al. Hashimoto's Thyroiditis impairs embryo implantation by compromising endometrial morphology and receptivity markers in euthyroid mice.  Reproductive Biology and Endocrinology, 2019, 17:94

   
   

7. Tang J et al. Effects of Vitamin D supplementation on autoantibodies and thyroid function in patients with Hashimoto’s Thyroiditis. A Systemin review and meta analysis. Dec 29, 2023, Medicine (Baltimore), Sourced from Pubmed.

   
   

8. Bich N B et al. The Endometrial Microbiota of women with or without a live birth, within 12 months after a first failed IVF/ICSI cycle. Scientific reports 13, article number 3444, 1 March 2023. Sourced from nature.com.

9. Bich N B et al. The Endometrial Microbiota of women with or without a live birth, within 12 months after a first failed IVF/ICSI cycle. Scientific reports 13, article number 3444, 1 March 2023. Sourced from nature.com.