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Thyroid UK
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Recently diagnosed and trying for a baby


I have just been diagnosed with an under active thyroid by my GP and i am 31 years old, my TSH was 6.4.

when it was last checked 4 months ago my TSH was 4. I don't understand how it has increased so much?

I attended as i have not had a period for 4 months, and we are trying for a baby.

i feel very anxious about everything now, and hoping that this will help my cycles return to normal. I have been put on 25mcg of levothyroxine, and have to return for a blood test in 6-8 weeks.

feeling worried.

6 Replies

Your TSH will have increased because your thyroid gland is failing, and your pituitary gland is pumping out more Thyroid Stimulating Hormone to encourage your thyroid to produce the thyroid hormones that every cell in your body needs. Also you may have the autoimmune condition Hashimoto's thyroiditis, (mostly) evidenced by antibodies in your blood, and the TSH rising can be evidence of an autoimmune attack - has your Dr tested for antibodies? 25 mcg is only a tiny starter dose for the very old, very young, or those with heart disease, and presuming you aren't any of those, the minimum you should have been started on is 50 mcg. Until your thyroid levels are such that you are euthyroid, it is important that you don't become pregnant - for the first few weeks of pregnancy the foetus is dependent on mother's thyroid hormone supply as it cannot generate its own, so would therefore be a drain on you. But more importantly, adequate thyroid hormones are critical for baby's development. The foetal central nervous system is sensitive to the maternal thyroid status. Critical amounts of maternal T3 and T4 must be transported across the placenta to the fetus to ensure the correct development of the brain throughout ontogeny.


Hello,Thank you very much for your quick response.

I havnt been tested for antibodies, i have asked for that and gp has said she will test it in 6 weeks at my next blood test.

My T4 was 14, not sure what that shows.

I dont have any other medical problems, so not sure why the low dose. I will speak to her about this.



You have posted this twice ! - I have replied on the other thread :-)

1 like

Why did you post twice?


sorry i am new to this and could not see where my first post had gone, i have figured it out now.



Have you told your GP you are trying to conceive? You will need a higher dose than 25mcg to bring TSH down to the low-normal 0.4 - 2.5 recommended for women planning conception.

When pregnancy is confirmed dose is usually increased by 25-50mcg to ensure good foetal development. NICE also recommends that hypothyroid women planning pregnancy should be referred to endocrinology. cks.nice.org.uk/hypothyroid...

Management of primary hypothyroidism: statement by the British Thyroid Association Executive Committee

13. The serum TSH reference range in pregnancy is 0·4–2·5 mU/l in the first trimester and 0·4–3·0 mU/l in the second and third trimesters or should be based on the trimester-specific reference range for the population if available. These reference ranges should be achieved where possible with appropriate doses of L-T4 preconception and most importantly in the first trimester (1/++0). L-T4/L-T3 combination therapy is not recommended in pregnancy (1/+00).


According the ATA First Trimester TSH levels between 2.5 and 5.0 are associated with increased pregnancy loss


For maximum absorption Levothyroxine should be taken with water 1 hour before, or 2 hours after, food and drink, 2 hours away from other medication and supplements, and 4 hours away from calcium, iron, vitamin D supplements, magnesium and oestrogen.

It takes 7-10 days for Levothyroxine to be absorbed before it starts working and it will take up to six weeks to feel the full impact of the dose. Symptoms may lag behind good biochemistry by several months.

You should have a follow up thyroid test 6-8 weeks after starting Levothyroxine. Arrange an early morning and fasting (water only) blood draw when TSH is highest, and take Levothyroxine after your blood draw.



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