Thyroid disorders in pregnant women can be associated with an increased risk of miscarriage, preterm labour, poor growth of the baby and stillbirth as well as poor mental development and low IQs in surviving offspring. Even mild forms of thyroid disorders, where the mother is unaware that she has the condition, are associated with these risks. Maternal thyroid disorders affect up to 5% of pregnancies in iodine replete regions like the UK, and significantly more pregnancies are affected in the 54 countries designated as markedly iodine deficient by the World Health Organisation.

The mother’s thyroid hormones reach the baby by crossing the placenta and both placenta and baby require thyroid hormones for normal development. There is a newly discovered protein which can transport thyroid hormones from one location to another and the researchers will study the role of this protein in the placenta. The study will assess how this is changed in pregnancies complicated by poor growth. The results should contribute to the debate about whether all pregnant women need tests to find out if they have thyroid disease. The ultimate aim is to improve the way doctors treat thyroid disorders and poor growth and development of the baby during pregnancy.