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Thyroid facts

Pregnancy and Your Thyroid Health

    Before you think about planning a family, how is your thyroid health?

    • The Australian Thyroid Foundation recommend all women of childbearing age be aware of their thyroid function pathology levels, family thyroid history and daily iodine intake.
    • Thyroid function (TSH level) and Autoimmune Disease testing (thyroid auto antibodies TPO & TGO) are recommended to rule out a thyroid disorder during this life stage. These tests are best done prior to conception or as early as possible in pregnancy, particularly if there is any suspicion or concern about a thyroid disorder. If necessary, a Thyroid Ultrasound can be ordered to rule out any physical change to your thyroid gland.
    • Adequate thyroid hormone levels at conception, during pregnancy and whilst breastfeeding is essential to protect your gestational health and for optimal foetal development.
    • For a successful pregnancy, it is vitally important to ensure your daily diet includes an adequate iodine intake and you include a daily pregnancy supplement containing at least 150mcgs of iodine before conception and throughout pregnancy and breastfeeding.

      Thyroid Autoimmune Disease

      It is important to know if you are genetically predisposed to Hashimoto’s or Graves’ Disease

      If you have a family history of these autoimmune thyroid disorders, it is important to ensure you can convey this information to your medical attendants so that they can order you the appropriate thyroid tests.

      • Autoimmune disorders may predispose you to a thyroid problem during pregnancy or in the postpartum period after giving birth to your baby.
      • Hypothyroidism occurring during pregnancy can be a serious threat to your pregnancy and the survival and intellectual function of the child.
      • A Thyroid Ultrasound may be ordered to determine any physical abnormalities of the thyroid gland due to a Thyroid Autoimmune Disease

      Iodine Deficiency During Pregnancy

      An increase in iodine intake is required during pregnancy from 150 ug daily in the non-pregnant state to 250 ug daily while pregnant. When contemplating pregnancy, during pregnancy and whilst breastfeeding please be aware of the National Health Medical Research Committee’s (NHMRC) recommendation to ingest a daily supplement of 150mcgs of Iodine which will help protect your thyroid health during pregnancy and your foetus’s development. Iodine is essential for both the maternal and foetal thyroid glands to produce T3 and T4. The foetus relies on its mother’s intake of iodine for its development.

      Australian research states 50% of pregnancy and breastfeeding women are mildly to moderately iodine deficient. An adequate daily intake of iodine enriched foods with a Pregnancy Supplement including at least 150mcgs of iodine is recommended. The iodine supplement should be continued while breastfeeding.

      Both inadequate thyroid function and iodine deficiency can affect the development of the foetal brain of your baby and lead to low intelligence and learning difficulties in children. All children are entitled to enjoy the life they were intended.

      Please read the publications below:

      References: Alexander EK et al., “2017 Guidelines of American Thyroid Association for diagnosis and management of thyroid disorders in pregnancy and the postpartum”. Thyroid Volume 27:315-389. Eastman CJ and Blumenthal N. “Gestational Subclinical Hypothyroidism”, Chapter 7, In Thyroid Diseases in Pregnancy Edited by F Azizi, Springer Books 2022e they were intended.

      Thyroid Pathology Tests

      If you are considering pregnancy, or if you are pregnant or breastfeeding, it is important your thyroid function is tested, monitored, and treated if necessary.

      • TSH - Thyroid Stimulating Hormone stimulates the thyroid gland and is secreted by the Pituitary gland.
      • T4 - the amount of Thyroid Hormone your thyroid gland is producing.
      • T3 - Triiodothyronine is the biologically active thyroid hormone secreted directly by the thyroid but derived mainly from conversion of T4 to T3 by enzymes in body tissues.
      • Thyroid Antibodies TPO & TGO - Antibodies directed against specific components of the thyroid gland causing autoimmune thyroid disorders such as Hashimoto’s or Graves’ diseases.

      Thyroid Function Tests during Pregnancy

      The normal reference ranges for TSH and T4 (free and total) during pregnancy differ from those in non-pregnant women because of the effects of pregnancy hormones on thyroid function. These test results also change with the trimester of pregnancy and may vary from one laboratory to another due to the analytical methods used to measure TSH and Free T4. Accredited Pathology laboratories will report TSH and Free T4 levels in a pregnant woman according to their locally derived, trimester specific, reference ranges using a specific analytical method. Because comparison of test results between laboratories can be misleading it is wise to always have the tests performed by the same laboratory.

      Mother’s Gestational Health

      The latest research published in The Lancet in March 2022 promotes the importance of the mother’s adequate thyroid health and avoidance of even mild or subclinical hypothyroidism to prevent the risk of gestational hypertension and pre-eclampsia. This recent research emphasises that hypertensive disorders of pregnancy, including gestational hypertension and preeclampsia or eclampsia, affect around 10% of pregnant women and are one of the leading causes of maternal and neonatal mortality and morbidity worldwide and that women suffering hypertension during pregnancy are at increased risk of long-term cardiovascular consequences and hypertensive disorders in subsequent pregnancies, and evidence suggests a risk of reduced cognitive ability in their offspring.

      This most recent research in the field of thyroid disorders in pregnancy highlights the importance of early detection and treatment of even mild degrees of hypothyroidism in pregnancy.

      References: Toloza F et al 2022: “Association between maternal thyroid function and risk of gestational hypertension and pre-eclampsia: a systematic review and meta-analysis. Lancet March 4, 2022. Stagnaro-Green A 2022. Commentary: “Thyroid disease in pregnancy: a touch of Clarity”. Thyroid, Vol 32 (4) 2022. Chen J, Zhu J, Huang X, Zhao S, Xiang H, Zhou P, Zhou T, Xu Z 2022 “ Subclinical hypothyroidism with negative for thyroid peroxidase antibodies in pregnancy: Intellectual development of offspring”. Thyroid 32:449–458.

      Heel Prick Test – Diagnosis of Congenital Hypothyroidism

      Congenital Hypothyroidism usually results when a baby is born without a thyroid gland, but there are many other causes of this disorder.

      Newborn detection of Congenital Hypothyroidism is determined by way of the Newborn Heel Prick Test. This test is usually done on Day 2-3 of life and is essential to determine genetic disorders in the newborn.

      The Heel Prick Test includes the TSH (Thyroid Stimulating Hormone) test which will determine your newborn’s thyroid health status. This test should be performed routinely on all newborn babies throughout Australia. Without this test, a thyroid disorder could easily be overlooked.

      Congenital Hypothyroidism is treated the same as hypothyroidism in children or adults, with a prescribed dose of thyroid replacement hormone, Levothyroxine. It is crucial for these babies to be diagnosed within a few days of birth by a newborn screening (heel prick) test as any delay can lead to loss of IQ.

      As babies grow, monitoring is necessary to adjust Levothyroxine dosage and to monitor growth and development. Ensuring ongoing Thyroid Pathology tests are performed in the correct manner is essential to ensure the dose of Levothyroxine is adequate.

      Children who have been diagnosed with Congenital Hypothyroidism are treated by a Paediatric Endocrinologist with regular monitoring and testing through their developing years.

      BE AWARE!

      If you are considering pregnancy, or if you are pregnant or breastfeeding, it is important your thyroid function is tested, regularly monitored and treated if necessary and a daily intake of iodine is essential to protect your pregnancy and development of your foetus.

      Good Thyroid Health during Pregnancy and Breastfeeding are essential!


      The Australian Thyroid Foundation recommend that all women of childbearing years, understand the importance of their thyroid health status when contemplating pregnancy, and while pregnant and breastfeeding.

      Determine your thyroid health before you conceive and once your pregnancy is confirmed. It is essential for your gestational health and the development of your newborn. Ongoing monitoring and treatment if needed should be continued to ensure you and your newborn’s health is protected.

      Safeguard your pregnancy and newborn development. Please speak to your GP and Obstetrician and ask for all the relevant thyroid pathology tests to be ordered before you conceive and once your pregnancy is confirmed. As previously emphasised, blood test results may vary from one laboratory to another so try to stick with the same accredited laboratory for all testing. Ongoing monitoring during pregnancy and treatment should not be overlooked if needed.

      If a thyroid disorder is determined, close pathology monitoring and treatment are essential. A referral to an endocrinologist who specialises in Thyroid Disorders during Pregnancy is recommended.



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      The mission of The Australian Thyroid Foundation Ltd (ATF) is to offer support, information and education to members and their families through the many services provided by The ATF and raise awareness about health consequences of iodine deficiency and the benefits of good thyroid health.

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