Peer Reviewed
Feature Article Obstetrics and gynaecology
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Recognising and managing thyroid dysfunction in pregnancy

Veronica A Preda, Diana L Learoyd
During pregnancy the production and metabolism of thyroid hormone change. Appropriate monitoring of thyroid-stimulating hormone levels with trimester-specific reference ranges is essential to avoid adverse effects in the pregnant woman and fetus.
Key Points
  • Thyroid hormone production and metabolism change with pregnancy.
  • Iodine supplementation is advised in most women during pregnancy to meet guideline recommendations for nutritional intake.
  • All women should be screened for thyroid dysfunction using a thyroid-stimulating hormone measurement during early pregnancy. At-risk groups will require more frequent monitoring throughout the pregnancy.
  • Women taking thyroxine replacement before pregnancy will usually require a dose increase of 30 to 50% in the first trimester.
  • Thyroxine replacement should be taken separately to other vitamins, including iron and calcium supplements, because binding can occur, decreasing the efficacy of absorption.
  • It is essential that women with thyroid dysfunction before or during pregnancy be seen by their GP in the postpartum period for follow-up assessment of their thyroid function.

    Picture credit: © iStockphoto/Skynesher. Model used for illustrative purposes only.

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