Thyroid UK
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Thyroid going wrong in pregnancy

Hi, I have hashimotos and have been on 75mg thyroxine for about 8 months. my TSH was sitting at 1.7. I still had symptoms but lots had improved. since I have been pregnant my tsh has dropped to 0.73.

I know this is still in range but the doctor had said to me i would probably need to increase thyroxine during pregnancy as Tsh should go up. so does anyone know why is gone down?

Also, I'm feeling cold alot and tired, breathless again which i had hyperthyroid (after last pregnancy). I'm worried about going hyper again, it was horrible.

Why is my body doing the opposite of what is supposed to happen?

6 Replies


Sometimes thyroid function improves during pregnancy. The baby will have developed his/her own working thyroid by 12 weeks so is no longer dependent on your thyroid hormone and that may, in part, explain why your TSH has dropped. TSH 0.73 is a good level for most people who would find 1.7 too high.

Feeling cold, tired and breathless can be hypothyroid symptoms but fatigue and breathlessness can also be due to pregnancy. TSH 0.73 doesn't indicate you are over medicated.


Thanks the level of0.73 was taken at only 8/9 weeks and before that at 2 weeks pregnant it was 1.25. so had been dropping since getting pregnant but still at the point when baby is using my thyroid.



TSH dropping is simply a sign that the pituitary gland has detected sufficient circulating FT4 and FT3.

Has TSH not been tested during the third trimester?


I'm not in third trimester. only about 10/11 weeks pregnant now. Sorry think my post was confusing!


Also my thyroid aching/hurting recently?!


I don't gave any answers but there is a great Facebook group that I have learned a lot from called FTPO-thyroid topics, Hashimoto's. Google it, being sure to include Facebook when you search. They can answer your questions. FTPO is; for the patient only. It's a closed group so ask to join and they will admit you once they see that you are a real person and not a MLM scammer.

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