T3 only and pregnancy

[yuliyam]

Hello I am currently taking T3-only (50 mcg), feeling great, and as my period (sorry, tmi) stabilized, my husband and I are thinking of trying for a baby. I know thyroid hormones are important for the development of a baby, but would 50 mcg be enough? Is it ok that my thyroid is suppressed? (or rather my TSH is suppressed, I have low T4 and T3 in optimal range). Maybe someone had an experience or has knowledge about it. Thank you xxx

[humanbean]

Doctors are usually not happy with women who go through pregnancy taking any T3 at all, never mind T3 only because they believe that the only thyroid hormone to cross the placenta is T4. They claim that T3 doesn't cross the placenta.

There has been one post that I can remember on this forum of a woman saying she had gone through a successful pregnancy on T3 only, but sadly I never bookmarked it and have never been able to find it again since. It may have been deleted for all I know.

There have been some mentions of successful pregnancies on NDT, which contains T3. And before Levo and T3 (as treatments for hypothyroidism) existed the only treatment for hypothyroidism was NDT, so there must have been many, many thousands of successful pregnancies on NDT.

Some threads that may be of interest :

healthunlocked.com/thyroidu...

healthunlocked.com/thyroidu...

healthunlocked.com/thyroidu...

You might also be interested in this paper entitled "Thyroid function in pregnancy"

ncbi.nlm.nih.gov/pmc/articl...

Please don't ask me to explain the paper - I only got the gist of a tiny proportion of it.

This might also be of interest - a paper entitled "The role of the placenta in thyroid hormone delivery to the fetus"

researchgate.net/publicatio...

Another paper :

sci-hub.tw/https://doi.org/...

Title : Placental transport of thyroid hormone

Sorry I can't help very much, and I certainly can't advise you what to do. I have no medical training at all.

[yuliyam in reply to humanbean]

Thank you, you are amazing!

[humanbean in reply to yuliyam]

You're welcome.

[humanbean]

You might find this of interest, but it is very long :

Title : Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum

Link : ncbi.nlm.nih.gov/pmc/articl...

[mfinn]

This from Endocrine Abstracts might be of interest. Normal neurodevelopment of children from a mother treated with only Liothyronine (T3) during pregnancy - a case report. Perhaps the belief that T3 doesn't cross over into baby is, like other thyroid information, wrong. endocrine-abstracts.org/ea/...

[yuliyam in reply to mfinn]

Thank you xxx