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Your Thyroid + How it Impacts Conception + Pregnancy

Does my thyroid health impair my chances of conceiving and or staying pregnant?

The short answer is Yes.

The longer answer is –

The first thing that is considered is your TSH. Whilst the range is 0.5-4.00, we ideally want to see TSH between 1.5-2.5 (in reproductive age). Having it within this range can optimise fertility, and IVF chances. We do not want TSH above 4.

A high TSH can indicate a low thyroid function (hypothyroidism).

We can also test the thyroid antibodies – higher antibodies increase miscarriage, hypertension in pregnancy, preeclampsia and postpartum haemorrhage. Suffice to say, this alone is a good enough reason to be on top of thyroid health before conception.

If antibodies are positive, we treat directly.

+ If antibodies are elevated, then our focus is to treat them, checking in every 4 weeks and each trimester.

The tests we do for thyroid are:






TG Abs

Furthermore, it’s important we look at your Vitamin D, Calcium, Iodine and do a full blood test. Often we would be looking at your liver as well.

Vitamin D is an immune modulator and it’s typically lower in those with hypothyroidism – having low D could be the culprit for your inability to regulate your thyroid.

We also need vitamin D in pregnancy and breastfeeding!

So how does thyroid function impact fertility?

Both hypothyroidism + hyperthyroidism can impair chances of falling pregnant and staying pregnant.

TSH can interfere with ovulation, making it harder to conceive. Autoimmunity (if thyroid condition is autoimmune in your circumstance), can also cause difficulty with egg fertilisation, implantation and increase risk of miscarriage.

It sounds all doom + gloom, but it isn’t!!

It’s important to work with your doctor to ensure you’re on the correct dose of medication (if on meds). If you aren’t sure it IS your thyroid making things hard to conceive + carry – get it tested and with the help of a thyroid qualified CAM practitioner (hello), to help you with the results and the potential treatment, before conception.

It is important for those wanting to conceive to be able to maintain sufficient iodine levels to maintain euthyroidism (normal thyroid function that occurs with normal serum levels of TSH and T4).

The WHO recommends iodine intake during pregnancy is 250 μg/day.

The NHMRC (2010) recommends that ‘all women who are pregnant, breastfeeding or considering pregnancy, take an iodine supplement of 150μg/day)’

A median urinary iodine concentration for pregnant women should be 150 – 249 μg/L.

Iodine requirements during pregnancy increase by approximately 50% due to greater migration of iodine to the foetus for adequate production of foetal thyroid hormone (especially in later gestation).

So to sum that up!! Women with or without a thyroid condition will typically require to supplement with iodine (please do not self prescribe this, especially if you have a known thyroid condition). Prenatal exposure to excess iodine results in goitre & hypothyroidism in the newborn - so please, do not take any unnecessary vitamins without consulting with your healthcare provider/s.

Iodine is required for our thyroid hormones (T3 conversion to T4). Thyroid hormone is required for normal neuronal migration and myelination of the brain during foetal and early postnatal life.

Low levels of thyroid hormone during this critical time can result in Cretinism.

In addition to consideration of iodine levels, in thyroid conditions us CAM practitioners will also consider selenium, vitamin D, myo-inositol to name a few. It can be really impactful to speak with someone with your most recent test results so you are getting the right therapeutic intervention with your diet, supplements, lifestyle advice and helping to correct thyroid picture, with the help of your doctor.


Mahan, L Escott-Stump, S 2008, Krause’s Food & Nutrition Therapy, 12th ed. Saunders Elsevier, Canada

Dr Aviva Romm MD: on Health Podcast episode 46

Shils ME Shike, M Ross, CA Caballero, B & Cousins, RJ 2006, Modern nutrition in health and disease. 10th ed. Lippincott Williams & Wilkins, Baltimore.

Zimmermann, M. 2012 ‘The effects of Iodine deficiency in pregnancy and infancy’ Paediatric and perinatal epidemiology. Vol 26(1), pp. 108 – 117

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