Thyroid UK
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Miscarriage and underactive thyroid

Hi everyone. First time here, currently having second mc and it dawned on me is it my T3 causing the problem. We struggled to conceive our healthy 28 month old, but since that I have not been able to carry a baby pass 1st trimester. Got a scan today so thought if I have a few questions to throw their way it may keep my emotions at a bay while they tell me the foetus has passed. Any advice or stories welcome. Thank you in advance x

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Hi Cnancjam. I'm very sorry to read that you've lost your foetus. After I was diagnosed with hypothyroidism, my endo kept a close eye on my thyroid levels and only gave me the go-ahead to get pregnant once she was happy I was stable. The moment I knew I was pregnant (within 4 weeks or so) I called her and she told me to increase my thyrax. Increasing the thyrax is important as the foetus is dependent on your thyrax for the first 16 weeks. Insufficient thyrax in the foetus can lead to developmental delays in a child. I was monitored by her the entire pregnancy. I decreased the thyrax to the original amount the day after my baby was born.

Are you being monitored by someone? Are your thyroid levels sufficient to sustain a pregnancy?

Good luck at your scan today.

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I'm sorry you have miscarried again and it is very upsetting.

This link may be informative and helpful:


I'm so so sorry to hear. Hugs and hope u get some good care next time xx



I'm so sorry you're miscarrying.

The TSH of pregnant women needs to be in the low normal range 0.4 - 2.5. >2.5 increases the risk of miscarriage. If you are taking sufficient T3 I doubt it will be causing miscarriage but most endocrinologists in the UK will try to persuade women to switch to Levothyroxine for the duration of the pregnancy.

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