Thyroid problems can be at the root of miscarriage and premature birth

In conventional medicine it is my experience that we tend to struggle a bit with the diagnosis and management of certain conditions, and near the top of the list (again, in my experience) is low thyroid function (hypothyroidism). Conventional wisdom dictates that ‘normal’ levels of thyroid hormones mean normal thyroid function. The ‘screening’ test for thyroid function is to measure ‘thyroid stimulating hormone’ (TSH). Raised levels of this point to low thyroid function. However, there is evidence that TSH is not as utterly reliable as an indicator of thyroid function or marker of health, and I’ve written previously about some of the issues here, here and here.

I’ve known for a long time that, in practice, it’s wise to assess individuals biochemically, but at the same time it’s crucial to take into account the clinical picture too. Failure to do this, in my view, can result in individuals suffering needlessly. And the symptoms of hypothyroidism are not just a minor inconvenience either. They can include: weight gain, fatigue, low mood and depression, mental lethargy, generalised swelling (known as ‘myxoedema’), sensitivity to cold, dry skin, dry hair, thinning of the hair and constipation. It’s unusual for hypothyroid individuals to exhibit all these symptoms, but it’s not uncommon for them to exhibit many of them.

In more recent times, I’ve become increasingly aware that it’s generally a good idea to check levels of ‘thyroid auto-antibodies’. These antibodies are made by the body in response to substances involved in thyroid function. The two most commonly tested antibodies when hypothyroidism is being suspected are anti thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG). I think it’s fair to say that most endocrinologists (hormone disorder specialists) would not treat a person with positive antibodies who also has a normal TSH level. However, I doubt that this is the best way, particularly having read this book. The book focuses on the most common form of hypothyoidism known as ‘Hashimoto’s Disease’. One may point made by the book as that standard blood tests are not to be relied upon. It also recommends management of the immune dysfunction that appears to be at the root of the disease. One key strategy here is to avoid gluten (in foods such as wheat, oats, rye and barley). For more details, see the book!

The relevance of thyroid antibodies was again highlighted this week on the publication of a study in the British Medical Journal [1]. In this review, the relationship between thyroid autoantibodies and miscarriage and preterm (premature) birth was assessed. Pre-term birth was defined, in this review, as birth occurring from between 24 and 37 weeks gestation.

Here’s a summary of the findings of this review:

1.     Evidence from ‘cohort’ studies (generally recognised as the best type of ‘epidemiological’ evidence) showed that the presence of thyroid autoantibodies was associated with a 390 per cent increased risk of miscarriage (i.e. risk was almost 4 times that in individuals without antibodies).

2.     Evidence from ‘case-control’ studies (generally regarded as inferior to cohort studies) risk of miscarriage was raised by 80 per cent in individuals with thyroid autoantibodies).

3.     The presence of autoantibodies was associated with a more than doubling in risk of pre-term birth.

The authors of the review offer two potential explanations for how a positive antibody status might affect pregnancy:

Firstly, the presence of thyroid autoantibodies in women with normal thyroid function could be associated with a subtle deficiency in the availability of thyroid hormones (a fall in circulating free thyroid hormones within the reference range) or a lower capacity of the thyroid gland to adequately rise to the demand for augmented synthesis of thyroid hormones required in pregnancy. Given that minor perturbations in thyroxine concentrations within the normal range can lead to an association between thyroid autoantibodies and adverse pregnancy outcomes, trials have been conducted to evaluate the effects of supplementation with levothyroxine on pregnancy outcomes in women with normal thyroid function who tested positive for thyroid autoantibodies. Secondly, thyroid autoantibodies might be an indicator of an underlying enhanced global autoimmune state. This itself can have a direct adverse effect on placental or fetal development.

Notice here there is mention of treating those with positive antibodies with levothyroxine (the stand drug/hormone used to treat hypothyroidism). The review goes on to report on the results of these trials: overall, treatment with levothyroxine roughly halves the risk of miscarriage.

Of what use is all this information? If you or someone you know has had a miscarriage or pre-term delivery (or perhaps more than one) and is planning pregnancy (however far off this may be), I suggest having a full thyroid ‘work-up’ including levels of TSH, free T4 and free T3. I recommend, obviously, that thyroid autoantibodies be checked too.

If your doctor expresses scepticism regarding the need for these tests, show him or her the study I’m reporting here. Click this link for a full text version of it.

In Malta recently I suggested that someone have her antibodies checked as I suspected hypothyroidism. The lab refused to do the test. Why? Because the TSH was normal. The problem, as I see it, is that people who work in labs generally haven’t seen enough patients, and don’t appreciate just how limited in value the TSH test is in practice.


1. Thangaratinam S, et al. Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence. BMJ 2011; 342:d261

11 Responses to Thyroid problems can be at the root of miscarriage and premature birth

  1. Bill 10 May 2011 at 6:25 pm #

    My endocrinologist takes this one step further: any patient presenting with signs and symptoms consistent with hypothyroidism gets a trial of thyroid hormone regardless of their bloodwork (unless it shows they’re hyperthyroid). He has found that bloodwork, including antibody levels, has too many false negatives, and a massive amount of suffering results when the “subclinical” hypothyroidism goes untreated. The results of the thyroid hormone trial help guide further treatment decisions.

    Often, the results are dramatic. As he likes to say, he’s gotten a lot of women pregnant this way :-). And helped many others whom other doctors would not treat.

    It’s highly unconventional, but since a short-term, low-dose trial of thyroid hormone is safe (assuming you’re not hyperthyroid), and the results of untreated hypothyroidism are so devastating, he has found it to be the best approach for his patients.

  2. John Briffa 10 May 2011 at 6:47 pm #


    That line about getting women pregnant made my laugh!

    Seriously, though, I find most endocrinologists ‘treat the numbers’. In my world, your endo would be a rare bird indeed. If only there were more like him….

  3. Paul 10 May 2011 at 9:48 pm #

    I am delighted to read this blog.

    I have followed Roberto Negro’s papers in JCEM (see links) and the benefits (of universal screening and T4 treatment for Ab+ and/or TSH<2.5) seemed obvious (to a layman).

    Imagine the effect of universal screening of pregnant women for thyroid status and T4 (T3?) treatment where necessary plus following the vitamin D recommendations from Hollis / Wagner.

    I will try to plough through the BMJ paper tomorrow.

  4. Paul 10 May 2011 at 9:51 pm #

    Sorry >2.5, not <2.5.

  5. Bill 11 May 2011 at 11:27 am #

    John Briffa says:
    In my world, your endo would be a rare bird indeed. If only there were more like him….

    Yes, he is a rare bird, and he has more tricks up his sleeve. After many years experimenting with ways to help hypothyroid people (including himself), he has developed quite a unique approach. I suspect you would be very interested in reading his forthcoming book (his second) explaining his methods:

    Among his innovations are seasonal adjustment of thyroid hormone doses and combined use of T4 and natural (pig) thyroid extract. He has found that 100% T4 therapy, as practiced by conventional medicine, starves the body of T3 and leaves the great majority of hypothyroid patients feeling poorly their entire lives.

    On the other hand, he has found that exclusively giving Armour or other natural pig thyroid extract, as often practiced by holistic doctors, results in a big T3 overdose. People feel great initially as their T3 starvation resolves, but they wind up with T4 tissue depletion due to the T3 overdose and their well-being declines. So often, they are then told they have “adrenal fatigue,” fibromyalgia, or other conditions, which they might, but which in his experience generally resolve nicely when the right balance of T4 and T3 is achieved.

    Needs vary, but the great majority of people seem to do best on the usual synthetic T4 medication plus compounded, time-release thyroid extract with, overall, about 1.3% T3 relative to T4. The T3 is critical, but for most people pig thyroid extract alone, at about 20% T3, is way too much for us humans (especially since T3 is absorbed much better than T4 in the gut).

    Sorry, too much detail for a web post! But I can personally attest to the effectiveness of his methods, which his new book will explain in detail so anyone who wants to can try them. He has begged the big shot specialists around here (Boston area) to at least try his approach with patients who insist they still don’t feel well on conventional therapy, but so far no takers.

    By the way, he would say you are a rare bird, too!

  6. John Briffa 11 May 2011 at 12:51 pm #


    The idea of levo-thyroxine/glandular thyroid mix makes a lot of sense.

    I’ve pre-ordered the book. Have a feeling it’s going to be a mine of useful information.

    Thanks for sharing this information.

  7. Jane McWhirter 13 May 2011 at 4:43 pm #

    Dear John

    Could a father with hypothyroid predispose to miscarriage if the mother is fine – or wouldn’t it affect things at all? (I have friends for whom this is the case)
    Thanks for this very useful exchange everyone – I’ve preordered the book too.

  8. Mariel 14 May 2011 at 2:50 pm #

    Magnesium deficiency is widespread. Most supplements are poorly absorbed. Mg is necessary for thyroid function and much more. For example, low Mg prevents proper vitamin D production, and increased sunlight or D supplementation will lower the Mg further, making the person feel worse, not better.
    In a Mg deficient person temporary improvement from thyroid supplements can lead to adrenal exhaustion in the long run. The Mg blood test is not reliable. An excellent website is . Menopause cuts Mg levels, also. Mark Sircus writes excellent articles, and recommends Mg lotion applied to the skin or bath flakes.I use the Mg lotion from Ancient Minerals.

  9. Theresa Fout 16 May 2011 at 5:55 pm #

    Synthroid and its derivatives have caused immersurable harm to literally thousands of sufferers because of the medical professions lack of understanding and insistence on relying on “big Pharma” for their drug education. Natural porcine thyroid provides t3, t4, t1 and t2, just like our own healthy thyroids do. I almost died taking a synthetic thyroid repalcement! I am thriving and feel terrific these days on my nature throid. I suggest those who recommend synthetic thyroid replacement take the time to educate themselves. Start with You will find a wealth of excellent, ACCURATE information and help.

  10. Nicola 14 December 2012 at 2:52 am #

    I could really do with some help!
    I’m 44, have been taking levothyroxine 100 mcg since 97, and have just had 4 th miscarriage in 3 years.
    I have one healthy son, and he is 25!
    Both gynae and endocrinologist have said that Hashimotos does not affect pregnancy, so I will be referring them both to BMJ.
    I am fit, and have recently begun a palaeolithic diet.
    A little confused as to what supplements to take
    I would be greatful of your advice.


  1. Hashimoto’s and Miscarriage/Premature Birth « The Crunchy Pickle - 11 May 2011

    […] (Click here for an article that I appreciate on the topic of Hashimoto’s and fertility.  It is clear and concise and does an excellent job revealing why the thyroid is so key in fertility/pregnancy.  I hope it is helpful.) […]

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