Your thyroid gland is located near the front of your throat, and is responsible for secreting thyroid hormones. There are 2 types of thyroid hormones – thyroxine (T4) and tri-iodothyronine (T3). Both T4 and T3 hormones are made from iodine and tyrosine (an amino acid). Your body depends on thyroid hormones for regulation of your metabolism, blood calcium levels, energy production, fat metabolism, weight maintenance and many more. Around 1 in 20 people have some form of thyroid condition, so read on to find out more about what they are, and how to optimise your thyroid health so as to maximise your fertility


There are 2 main types of thyroid conditions – Hyperthyroidism and Hypothyroidism. Both hypo and hyper-thyrodisim can significantly affect your fertility.

In Hyperthyroidism, thyroid hormones are raised as a result of the thyroid gland producing too much thyroid hormones. This causes symptoms such as weight loss, heat intolerance and hypertension. One of the most common of hyperthyroidism is Grave’s disease, an auto-immune condition. When there is an excess of thyroxine produced, fertility hormones such as oestrogen and progesterone can be impacted. This can cause irregular ovulation and increased rates of miscarriage.

On the other hand, in Hypothyroidism, there is a thyroid deficiency due to the lack of thyroid hormones produced by the thyroid gland. This can lead to cold sensitivity, fatigue and potentially dry skin. In terms of its effect on fertility, hypothyroidism can cause irregular menstrual cycles and ovulation problems.

Good thyroid function is essential for fertility, conception and maintenance of a healthy pregnancy. Thyroid dysfunction in pregnancy is associated with a range of adverse obstetric outcomes such as miscarriage, pre-eclampsia, placental abruption, preterm birth and post-partum haemorrhage. It also poses risks to the baby, such as low birth weight, increase neonatal respiratory distress and decreased cognitive function.



Nutrition plays a major role in hypo and hyper-thyrodisim as dietary and lifestyle changes can help improve thyroid function and thyroid hormone production.


Iodine is a mineral that is an integral component of thyroxine (T4), as it is essential in the production of thyroid hormones. The recommended daily intake of iodine for women is 150 µg/day. Foods rich in iodine include seafood and fish; vegetables grown in iodine-rich soil, and iodised salt. In Australia, all commercial bread products (except organic bread and bread mixes) have been fortified with iodine. Be careful with iodine supplements especially for those who have Grave’s disease; and always check with your doctor first before starting on iodine supplements.



Goitrogens or goitrins are found in high amounts in cruciferous vegetables (cabbage, broccoli, brussels sprouts), soy, and grains such as millet. The excessive consumption of these vegetables can block the absorption of iodine as goitrins can interfere with the production of thyroid hormones (usually with iodine deficiency). However, the good news is that the effect of goitrins are reduced once those cruciferous vegetables are cooked, so continue to eat those vegetables, just be sure to cook them.

Weight and Exercise

Weight is a huge factor in both hypo- and hyper-thyroidism. Hypothyroidism can make it difficult to lose weight as it slows down your body’s metabolism. For women with hypothyroidism, focus on eating well and working on your metabolism. Physical activity can help to increase your muscle mass, so ensure that you eat enough protein foods and engage in regular exercise.

Increased metabolism due to Hyperthyroidism can mean that you may lose weight and muscle mass quickly. Therefore, exercise is important to maintain muscles mass. Exercise is beneficial as it will stimulate thyroid hormone secretion and increase tissue sensitivity to thyroid hormones, so make sure you stay active!


  1. Eat sufficient (but not in excess) iodine-rich foods, aim to have at least:
  • 2-3 serves of fish per week
  • 5 serves of vegetables & 2 serves of fruit per day
  • Wholegrains fortified with iodine
  1. Cook your cruciferous vegetables before eating them.
  2. Get moving! Aim for at least 30mins of physical activity at least 5 days a week. Any form of exercise that makes your breathing become quicker and heart beat faster is good. This can include walking, swimming, cycling, playing tennis, dancing etc.


Thyroid function and good levels of thyroid hormones is extremely important for optimising fertility. Your diet and lifestyle both play huge roles in this! If you’re trying to conceive or if you require more individualised advice about your thyroid function, get in contact with one of our Accredited Practising Dietitians. We can provide the support you need from fertility, to conception and throughout your pregnancy journey. You can book into one of our nearest clinics or contact us for online consults.