Thyroid disorders and growth restriction in pregnancy: could a newly discovered protein hold the key to better treatment?
This research was completed on 31 October 2010
Published on 22 October 2008
Thyroid disorders and restricted growth can both endanger the health of unborn babies. They're linked to miscarriage, stillbirth and premature birth. Some babies who survive can be left with long-term health problems, such as learning difficulties. Researchers are studying the role of a newly discovered protein called MCT10, which might be important to the action of thyroid hormones. They hope to increase understanding and pave the way for the development of better treatments.
What's the problem and who does it affect?
Unborn babies at risk
This project is tackling two distressing yet common problems that endanger the health of babies during pregnancy: thyroid disorders in expectant mothers and growth restriction of unborn babies.
Thyroid disorders affect up to 5% of pregnancies in the UK and even more in some other countries.1,2,3,4 They are linked to miscarriage, premature birth, bleeding from the placenta and poor growth of the baby during pregnancy. Some babies who survive have a low IQ and poor mental development. Babies can suffer even if their mother’s disorder is so mild she is unaware of it.
Babies with intrauterine growth restriction grow dangerously slowly in the womb. This common problem affects around 5-8% of pregnancies in the UK.5 The most severely affected babies have to be delivered prematurely to stop them from dying in the womb. Sadly, some still lose their lives and others develop ongoing health problems.
There are no effective treatments for unborn babies with fetal growth restriction and it’s not entirely clear how best to treat expectant mothers who have a thyroid disorder. Both conditions make pregnancy an extremely anxious time.
What is the project trying to achieve?
Is a newly discovered protein important?
Unborn babies need a supply of thyroid hormones from their mother if they are to develop properly during pregnancy. The placenta needs these hormones for its development too.
Thyroid hormones travel from the mother’s bloodstream through the placenta to the baby with the help of special proteins, called transporters.
A newly discovered transporter, called MCT10, seems particularly good at transporting thyroid hormones. Researchers suspect MCT10 may play a key role in the supply of thyroid hormones to unborn babies. They think it may also affect the growth and development of the placenta. What’s more, evidence suggests abnormally low levels of MCT10 may be linked to the poor growth of unborn babies who have growth restriction. In this project, researchers are testing their ideas about the importance of MCT10 in both normal pregnancies and pregnancies complicated by growth restriction.
They are using samples of placental tissue taken with consent from women at different stages of pregnancy.
What are the researchers' credentials?
|Project Leader||Professor M Kilby MD FRCOG|
|Location||Department of Obstetrics and Gynaecology, Division of Medical Sciences and Institute of Biomedical Research, University of Birmingham & Birmingham Women's Hospital|
|Grant awarded||22 July 2008|
|Start date||1 November 2008|
|End date||31 October 2010|
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The internationally renowned researchers working on this project are experts in the action of thyroid hormones in the human placenta. They have many recent, eminent publications to their name in peer-reviewed journals.
A strong and long-standing collaboration has boosted the success of this multidisciplinary team. The Project Leader, Professor Mark Kilby, specialises in studies of the fetus and placenta, while Professor Jayne Franklyn has extensive knowledge of the action of thyroid hormones.
The experiments will be conducted within the Institute of Biomedical Research (IBR), College of Medicine & Dentistry, University of Birmingham, where the laboratories have state-of-the-art facilities. The Institute is adjacent to the Birmingham Women’s Hospital (BWH), a tertiary referral hospital with one of the leading Fetal Medicine Departments in the country. The hospital manages 7,000 deliveries per year, providing good opportunities to obtain samples of placental tissue for research.
Who stands to benefit from this research and how?
Informing the debate
Thyroid disorders and growth restriction both put unborn babies’ health at risk. Researchers believe their work will help to explain how this happens, by revealing some of the molecular mechanisms involved within the placenta.
This important new information is badly needed. Controversy surrounds whether we should introduce routine screening of pregnant women for thyroid disorders in the UK. It’s possible that screening could ensure more women with mild disorders are identified and that treatment could then protect their babies, but this is hotly debated.
Even when disorders are detected, the best way to treat them is far from clear. Hormone replacement, which is simple and cheap, is sometimes a possibility. However even the basics of treatment, such as the most appropriate dose, are unclear. Researchers believe their work will contribute invaluable information to the debates about screening and treatment.
Hopes of new treatments
The information revealed in this project may also pave the way for the development of brand new treatments for both thyroid disorders and growth restriction. The ultimate hope is to find ways to protect babies from miscarriage, stillbirth and premature birth, and spare survivors from long-term problems, such as learning disabilities.
- LaFranchi SH, Haddow JE, Hollowell JG. Is thyroid inadequacy during gestation a risk factor for adverse pregnancy and developmental outcomes? Thyroid 2005;15(1):60-71.
- Haddow JE, Palomaki GE, Allan WC, Williams JR, Knight GJ, Gagnon J et al. Maternal thyroid deficiency during pregnancy and subsequent neuropsychological development of the child. N Engl J Med 1999;34(8):549-555.
- Lazarus JH, Premawardhana LD. Screening for thyroid disease in pregnancy. J Clin Pathol. 2005 May;58(5):449-52.
- WHO, ICCIDD & UNICEF. (2001) Assessment of Iodine Deficiency Disorders and Monitoring their Elimination. A guide for Programme Managers, 2nd edn [Online] ed: World Health Organization. Available at http://www.who.int/reproductive-health/docs/iodine_deficiency.pdf (accessed on 18 January 2007).
- Neerhof MG. Causes of intrauterine growth restriction. Clin Perinatol 1995; 22 (2): 375-85.