Why do miscarriages happen?

Many patients come to us with a history of miscarriages, generally at a loss as to why they are having miscarriages. The majority of them tell us their doctors do not seem to be that interested in helping them with this issue, with some doctors even dismiss miscarriages by saying, “well, it is something natural anyway; just try again”.

Scientific research shows there are potential causes (many of which do not seem to be amenable to standard Western medical treatment): age, hormonal, genetic, immunity, anatomical, to name but a few. (To read the studies themselves, please check out our Resources page here.)

Is age a factor in miscarriages? 

Age is the single most important factor cited by gynaecologists and IVF specialists when explaining the difficulties in conceiving naturally, IVF failures and miscarriages. This may be due to the fact that age is the best “predictor” for IVF success — though a predictor is not necessarily a cause. Age is associated with factors that are important to fertility, but age itself is not a medical diagnosis, for the simple reason that age is not a direct cause for disease or medical condition.

Age only causes an impact when it is mediated through something else. Consider dementia: Is age a predictor for dementia? Yes. The possibility of dementia increases with age. Is age the cause of dementia? No. Age does not directly cause dementia. The cause of dementia is brain degeneration, not age itself. The same applies to a range of medical conditions, such as high blood pressure, stroke, diabetes, etc. While all these conditions are associated with ageing, age is not the cause for all of these as there are other direct causes for each of them.

Curiously, when it comes to fertility, age’s part in it seems to be often elevated to be the actual cause of infertility. As far as we know, this is not backed up by science, logic or medical knowledge.

Genetics and miscarriages?

Patients tell us that when their IVF cycles fail, they are persuaded to carry out genetic tests to see if there may be genetic abnormalities. While there may well be genetic abnormalities in embryos that failed to develop, it is likely that the genetic issues are part and parcel of egg or sperm quality issues anyway. In any case, genetic issues found in embryos at hand are unlikely to mean similar genetic issues will appear in future embryos.

Should I be concerned about “killer cells”?

Some investigators in small retrospective trials have found a link between natural killer cells and pregnancy loss and implantation issues. However, the vast majority of large and well-constructed, high-quality studies fail to find such a link. Nonetheless, IVF clinics are increasing persuading patients to get tested and offer treatment regardless.

What about physical factors?

Common physical factors such as fibroids, endometriosis and adenomyosis, when found, are often cited as causes for miscarriages. While they may contribute to miscarriages, they are unlikely to be the key decisive factors in your infertility, unless that the conditions are severe — such as very large fibroids or severe adenomyosis.

What the NHS tends to do

The NHS tends to play down miscarriages. Our patients often tell us that their GPs tend to only refer them to specialists for further investigation after 2 or more miscarriages. When patients are referred, the gynaecologists may investigate physical causes such as fibroids, endometriosis, adenomyosis etc. It should be noted that, should physical causes be found, they are seldom the definitive reasons for recurring miscarriages. What we mean is that, while these causes may impact pregnancy, doctors are often uncertain whether they are the decisive factors (how much of a part they play in the infertility) — unless they are very serious, for example, very large fibroids.

Whether physical causes are found or not, gynaecologists are likely to suggest progesterone and aspirin — progesterone to thicken the lining of the uterus, and aspirin to thin the blood — when pregnancy happens again. The efficacy of these options is unclear.

Given these two drugs are routinely offered by IVF clinics after implantation, and implantation success rate has not improved significantly as a result, it is not immediately obvious that the thickening the lining of the uterus or thinning of blood helps. Many of our patients have told us they still have miscarriages after using progesterone and aspirin.

Can IVF help?

IVF had the advantage of making sure an egg meets a sperm. In the case of miscarriages, an egg has met a sperm and an embryo has developed, it is therefore unclear what IVF can add to the equation.

The main reason for IVF failure is failed implantation. This is rather like a miscarriage: If a patient’s problem is to keep the embryo in the womb, and many also find it difficult to do the same with IVF, we are compelled to conclude that IVF is unlikely to be a solution for recurring miscarriages.

What about changing diet and lifestyle?

Some patients come to us and say that they’ve made substantial changes to diet and lifestyle, and they feel like this has seemed to have brought some benefits. However, when we look at their hormone levels, many still suffer from hormonal imbalance. This is consistent with our clinical experience: While diet and lifestyle changes can help somewhat, these alone does not seem sufficient to bring hormones back to normal levels.

What about supplements?

Many patients use supplements before they come to us. They tend to be taking them on faith without pre- and post-treatment hormone-level testing. We may be wrong, but we are not aware of effective supplements that can reliably balance key reproductive hormone levels.

How egg quality affects miscarriages

At TCM Healthcare, our experience tells us that egg quality is by far the most common cause for miscarriages. We have found that most patients who have recurring miscarriages have imbalanced hormones. Hormonal imbalance implies poor egg quality: Once hormones improve, successful pregnancy follows.

Hormonal imbalance generally takes two broad forms. One involves imbalance of FSH, LH, prolactin and oestradiol. The typical pattern is high FSH, high LH, high prolactin and low oestradiol, which is usually associated with irregular or missing periods. 

The other form is to do with high AMH and high testosterone: This is usually associated with skin and hair issues, and sometimes irregular or missing periods. This form of hormonal imbalance is often misunderstood due to the questionable validity of AMH and testosterone’s reference ranges, as we wrote in a previous blog. Please click here for more details

In our experience, these two forms of hormonal imbalance explain a great majority of recurring miscarriages, we therefore find improving hormones is the key for treating recurring miscarriages successfully.

What should I do?

Since poor egg quality, a result of hormonal imbalance, is the main cause of recurring miscarriages, as a first step, you may wish to carry out some standard hormone tests to check your egg quality.

Click here to see what tests are recommended.

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