Association between thyroid autoantibodies and miscarriage

I'm sure this has been posted before but re-reading it this morning and feeling a range of emotions.. Happy that there is something in writing that I can show my doctors... But frustrated because I know that it won't be acknowledged. Thinking of printing this and taking it to my recurrent miscarriage clinic appointment on Monday. 

I'm on 25mg levothyroxine at the moment but think I should be on 50mg when I'm pregnant due to my high levels of antibodies and borderline tsh levels.

The paper described below is a summary of all the studies published on the relationship between thyroid antibodies and miscarriage.  


Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence

BMJ 2011; 342 doi:



To evaluate the association between thyroid autoantibodies and miscarriage and preterm birth in women with normal thyroid function. To assess the effect of treatment with levothyroxine on pregnancy outcomes in this group of women.


 30 articles with 31 studies (19 cohort and 12 case-control) involving 12 126 women assessed the association between thyroid autoantibodies and miscarriage. Five studies with 12 566 women evaluated the association with preterm birth. Of the 31 studies evaluating miscarriage, 28 showed a positive association between thyroid autoantibodies and miscarriage. Meta-analysis of the cohort studies showed more than tripling in the odds of miscarriage with the presence of thyroid autoantibodies (odds ratio 3.90, 95% confidence interval 2.48 to 6.12; P<0.001). For case-control studies the odds ratio for miscarriage was 1.80, 1.25 to 2.60; P=0.002). There was a significant doubling in the odds of preterm birth with the presence of thyroid autoantibodies (2.07, 1.17 to 3.68; P=0.01). Two randomised studies evaluated the effect of treatment with levothyroxine on miscarriage. Both showed a fall in miscarriage rates, and meta-analysis showed a significant 52% relative risk reduction in miscarriages with levothyroxine (relative risk 0.48, 0.25 to 0.92; P=0.03). One study reported on the effect of levothyroxine on the rate of preterm birth, and noted a 69% relative risk reduction (0.31, 0.11 to 0.90).


The presence of maternal thyroid autoantibodies is strongly associated with miscarriage and preterm delivery. There is evidence that treatment with levothyroxine can attenuate the risks.

24 Replies

  • Hi, sorry you have had miscarriages it's such a horrible thing to go through. I have 3 children and had 7 miscarriages and know it is linked to thyroid problems. Also I am aware that miscarriage can happen for other reasons. I was looking at an American study a few nights ago which said that thyroid meds need to be increased in early pregnancy by 30-50 percent until around week 16. Even though I had that many miscarriages I've never had any tests done and been back and forth about thyroid problems but never had that diagnosed either. That was done privately. 

  • Molliemoo1,

    NICE recommend the TSH of women planning conception and newly pregnant should be 0.4-2.0 with FT4 in the upper range.  Levothyroxine is usually increased by 25-50mcg when pregnancy is confirmed.

  • Thanks clutter, but unfortunately these guidelines only apply to women with official diagnosis of hypothyroidism or Subclinical Hypothyroidism and that appears to be a subject for debate in my case 

  • Molliemoo1,

    The advice applies to women planning conception.  If your GP doesn't understand that I would change doctors.

  • Clutter I can only find text that applies to women who are pregnant or planning a pregnancy who have hypothyroidism or Subclinical Hypothyroidism. Both my GP and private endo said that those guidelines don't apply to me as my tsh is in range. 

  • Molliemoo1,

    I think your GP is disingenuous.  The guidance clearly states that women planning conception and newly pregnant should have TSH in the low-normal range 0.4-2.0.

  • Clutter, please could you post the link for me to your reference? Thanks 

  • Molliemoo1,

     It's the link I posted above

  • thanks clutter, unfortunately it is as I suspected. The scenario context of the article is 

    "Scenario: Preconception or pregnant

    Scenario: Subclinical or overt hypothyroidism in the prenatal or antenatal period"

    All the sub headings either talk about overt or Subclinical Hypothyroidism.

  • Molliemoo1,

    "Aim for a TSH concentration in the low-normal range (0.4 mU/L to 2.0 mU/L) and an FT4 concentration in the upper reference range.

    If there is any uncertainty about what dose to prescribe, seek immediate specialist advice so that there is no delay in the woman receiving an adequate dose of levothyroxine."

    Two clear statements there.  If your TSH is >2.0 and you are trying to conceive or pregnancy is confirmed your GP should prescribe Levothyroxine.  If he doesn't know what dose to prescribe he should seek immediate specialist advice.

  • That text is under the heading "Pre-existing subclinical hypothyroidism

    How should I manage a woman with pre-existing subclinical hypothyroidism who is pregnant or planning a pregnancy?" 

    unfortunately... So only applies to women with subclinical hypothyroidism who are planning a pregnancy. 

    I agree with you in that comment sense would suggest that all pregnant women should have a TSH less than 2 but unfortunately that's not what the nice guidelines say. 

  • Don't get me wrong, I think women in my situation should still take these guidelines to their doctor to discuss, but just trying to manage expectations a little 

  • Molliemoo1,

    I don't agree with your GP that the guidelines are only applicable to women with existing subclinical or hypothyroid diagnoses. 

    The TSH range 0.4-2.0 is for women planning conception and newly pregnant, it doesn't matter what the headings are or whether the woman has an existing diagnosis if her TSH is higher than 2.0.

    Many women develop hypothyroidism during pregnancy and require treatment to bring TSH down to trimester specific levels.

  • I completely agree with what you're saying about thyroid and pregnancy, which is why I'm so worried myself after 2 miscarriages, high antibodies and a TSH about 2,but the guidelines don't say that they apply to euthyroid women. 

    Hopefully when the results of the Tablet trial are out, they will adapt the guidelines. 

  • *above not about 2

  • Molliemoo1,

    Euthyroid is just another way of saying within normal range.  TSH >2.0 in a range 0.35-5.0 is euthyroid for most women but is not euthyroid for women planning conception and pregnant who should have TSH in the low-normal range 0.4-2.0.

  • 25Mg is a very low dose for you to be on anyhow. Have you obtained any recent bloods at all to see what's going on? It could be that you are still not within range. Basically during early pregnancy the baby takes the majority of your thyroid hormoan so this is why to prevent miscarriage if your thyroid is low, medication needs to be increased as soon as pregnancy is confirmed. Thing is if you are not on the correct dose to begin with that can complecate issues further. I am convinced that my re currant miscarriages are down to thyroid problems. I assumed they were meant to monitor your thyroid levels more closely during pregnancy anyhow which it looks like they haven't been doing with you. 

  • Yes it's a very low dose but my tsh levels are in range x

  • Is your T4 and T3 within range do you know? My TSH was in range but my T4 was not and at the bottom of low. Hope you get it sorted it is an uphill struggle getting the NHS to listen.

  • Orangepie has a blog on miscarriage and thyroid


  • Molliemoo, so sorry you are going through this. Wishing you lots of luck in getting your doctors to listen. 

    I totally sympathise with your frustration that doctors cannot apply the logic of the NICE guidelines to all women. My TSH was almost 5 before my first cycle of IVF and I was patronised by my GP for being concerned. I returned with the NICE guidelines and was told that they only applied to women with subclinical or overt hypothyroidism which I blatantly wasn't (despite all the symptoms of hypothyroidism and positive antibodies). Changed GP. Same story. It took my fertility clinic (also NHS) writing to my GP and demanding treatment. Even then one GP was very scathing about me taking "unnecessary" medication and trotted out the horror story of osteoporosis and atrial fibrillation ... 

    I was at my fertility clinic yesterday and the nurse told me that all women should have a tsh below 2.5 (and ideally closer to 1) and should raise thyroxine immediately on a BFP by 25-50mcg. 25mcg does seem a small dose and seems to be one the fertility clinic favours for tsh just over the 2. I started on 50mcg and raised to 75mcg after 6 weeks. 

    I saw a report on the BBC website today where a woman was discovered to be hypothyroid after 4 miscarriages. Heartbreaking to think how much many of us suffer miscarriages that could be so easily avoided with decent medical care. 

  • Hi kayaktime 

    Thanks for your message. I have my first appointment at the recurrent miscarriage clinic tomorrow. I really really really hope that they are of the same understanding as the staff at your clinic. I'm not getting my hopes up but will keep my fingers crossed. 

    My endo wrote in a letter that I "clearly have subclinical hypothyroidism" but gps disagree. Im taking that letter as well as the nice guidelines with me and all of my test results. Any other tips for the appointment? 

  • Molliemoo, sounds like you have everything you need for your appointment. I think your clinic will be a lot more understanding and knowledgable than your GP and surely (hopefully) they'll value an endo's opinion over that of a GP. I have my fingers crossed for you that you get the answers and support you need tomorrow. This is all hard enough to deal with without worrying about doctors being ill informed and ignoring evidence. Let us know how you get on. x

  • Unfortunately, the doctor I saw wasn't aware of the nice guidelines and admitted she didn't know alot about thyroid so she is writing a letter to refer me to the endocrinologist at the hospital. 

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