Pregnancy and Screening for Thyroid Problems | Action Medical Research | Children's Charity

Should all pregnant women be screened for thyroid problems?

This research was completed on 31 December 2015

Published on 26 October 2012

Estimates suggest around five per cent of women have subclinical hypothyroidism, where the thyroid gland doesn’t seem to be working quite as well as it should.1 Although these women typically experience no noticeable symptoms, it’s possible the condition might put the future health of babies at risk if it goes undetected and untreated during pregnancy. Professor Marian Ludgate, of Cardiff University, is investigating whether routine screening and treatment of pregnant women for these thyroid problems benefits their children.

What is the problem and who does it affect?

Estimates suggest around one in twenty women have a mild problem with their thyroid gland, called subclinical hypothyroidism.1 Uncertainty surrounds how this problem influences the long-term health of babies if mothers are affected during pregnancy. It’s also unclear whether treating pregnant women benefits their babies.

“Some evidence suggests children are at increased risk of having a low IQ, and various emotional and behavioural problems, if their mother had mild thyroid problems during pregnancy,” says Professor Ludgate. “Other studies, however, have had contradictory findings. The lifelong consequences of having a low IQ can be quite considerable, with effects on employment prospects and income, and on social aspects of life, such as the likelihood of getting divorced or of going to prison.”

Mild thyroid problems can be treated. “Thyroid hormone replacement therapy is safe and inexpensive,” explains Professor Ludgate. “However, pregnant women in the UK are not routinely screened for thyroid problems. As these problems typically cause no noticeable symptoms, pregnant women who are affected might not realise anything is wrong. It is possible that their babies might be suffering long-term consequences unnecessarily.”

What is the project trying to achieve?

“We aim to establish whether screening pregnant women for mild thyroid problems, and treating those women who are found to be affected, offers any long-term benefits to their children,” explains Professor Ludgate.

Professor Ludgate is studying a group of women who took part in an earlier study, called CATS-I. During this study, 16,500 pregnant women from South Wales had their thyroid function tested – 700 were found to have suboptimal thyroid function and half of these women received treatment.

Up to 900 women from CATS-I are taking part in this new study, called CATS-II, with their children, who are now eight to ten years old.

“In this project, we are using a range of tests to assess the children’s IQ, behaviour, coordination and social skills. This complements other investigations we are running into the physical development of the children. We are confident that this combined approach will provide invaluable insight as to the potential benefits of thyroid screening in pregnancy – and tell us whether such screening should be offered as a matter of routine to all pregnant women – in the UK and worldwide.”

What are the researchers’ credentials?

Professor Ludgate is based at Cardiff University’s School of Medicine, which has a long and distinguished track record for its research into thyroid disorders. The importance of the original CATS study, for example, is illustrated by its publication in the New England Journal of Medicine, a highly prestigious medical journal.

Project LeaderProfessor Marian E Ludgate BSc PhD
Project team
  • Professor Colin M Dayan MA MBBS FRCP PhD
  • Professor John W Gregory MBChB MD FRCP FRCPCH DCH
  • Dr S Channon BSc D Clin Psych
  • Dr O E (Buchi) Okosieme MD MRCP MBBS
LocationInstitute of Molecular and Experimental Medicine, School of Medicine, Cardiff University
Other locations
  • Endocrine and Diabetes Department, Prince Charles Hospital, Mid Glamorgan, Wales
DurationTwo years
Grant awarded26 July 2012
Start date11 February 2013
End date31 December 2015
Grant amount£107,853.00
Grant codeGN2033
AcknowledgementsThis project is funded by a generous donation from The Henry Smith Charity.

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  1. Screening and Treatment of Subclinical Hypothyroidism or Hyperthyroidism, ‘Introduction’ Website accessed 10 October 2012.
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