Your Thyroid and Fertility Explained

In this article we are having a little look at the thyroid gland in relation to fertility.

In particular we are going to focus on thyroid autoimmunity.

Thyroids, Fertility & Autoimmunity

The thyroid hormones act on nearly every cell in your body and they are constantly interacting with the ovaries at all phases of your cycle and reproduction. Imbalances of the thyroid are not uncommon in women of reproductive age and they can affect fertility in various ways. These include issues with ovulation, implantation and sex hormone levels.

Working to have your thyroid tests at optimal levels is really important preconception care.

So what is tested?

Ideally you want to have the following blood tests done:

TSH- This is the hormone that stimulates the thyroid gland to produce thyroid hormone.
High levels are released when there are low levels of thyroid hormone and lower levels are seen when there is an abundance of thyroid hormone.
The ideal fertility range for TSH is 0.5-2.0mU/L

FT4- Free Thyroxine- This is the main form of thyroid hormone produced in the thyroid gland. It is known as the storage form of thyroid hormone.
The ideal range is 15-19pmol/L

FT3- Free Triiodothyronine- This is the active form of thyroid hormone. It comes both direct from the thyroid gland and also from the conversion of T4.
The ideal range is 4.5-5.6 pmol/L

TPO- Antithyroid Peroxidase- This is an enzyme required to make thyroid hormones. Antibodies that target this enzyme are TPO antibodies or TPOab.
Ideally <20 IU/ml

Antithyroglobulin Antibodies- This is a protein made in the thyroid gland that provides the site for the location of thyroid hormone. These antibodies target this protein.
Ideally <20 IU/ml

Important things to note

  1. Unfortunately more often than not just the TSH test is done which fails to give a full picture of what is going on in the thyroid.

  2. Often there can be problems with antibodies or thyroid hormone levels when the TSH is seen in ranges of 0.3-5.5 mU/L.

  3. **If you have a family history of thyroid issues or autoimmunity, you need your full thyroid tested including antibodies.

  4. You can also do a full thyroid test here. Just pay online, print, go to a pathology lab & results emailed to you in 3 days - yay!

How is it treated?

In Western medicine, high TSH is treated with the hormone replacement Levothyroxine.

This is a medication that mimics T4 hormone. This can be very effective at lowering TSH levels, increasing T4 and T3 production and can have an effect on lowering thyroid antibodies too.
It’s a delicate affair though and getting the right balance of medication can prove challenging for GPs and endocrinologists. When pregnancy is thrown into the picture there can be fluctuation and medication often needs to be adjusted.

From an Integrative Chinese Medicine perspective, we take more than just your thyroid into account whilst working alongside other health professionals. We treat the signs and symptoms you may be experiencing, talk about lifestyle and diet and consider necessary supplements that help the complicated thyroid processes to run smoothly.

When Thyroid Antibodies are high, but everything else in is range

Often in clinic, we see women with high thyroid antibodies who have ‘in range’ results on their other thyroid tests. This means they have some autoimmune processes going on (where the immune system mistakes part of your body as foreign & attacks it!) but they don’t yet fit the criteria for Levothyroxine.

These results, in themselves, can make the conception process a little more difficult and there is unfortunately a higher rate of miscarriage and preterm birth with autoimmunity present.


In clinic, we recommend Autoimmune Paleo Diet to help women to help themselves lower these antibody levels. You can read more here.

Have more questions about your thyroid and fertility?

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