Fertility and pregnancy outcomes in women screened for thyroid disease
Research type
Research Study
Full title
Investigating the fertility and pregnancy outcomes in women screened preconception for thyroid disease: an observational cohort study
IRAS ID
272213
Contact name
Rima Dhillon-Smith
Contact email
Sponsor organisation
University of Birmingham
Duration of Study in the UK
2 years, 0 months, 3 days
Research summary
Normal functioning of the thyroid gland is essential for successful conception and pregnancy. Subclinical
hypothyroidism (SCH) is a form of mild thyroid dysfunction and is a diagnosis given to those who have
normal levels of thyroid hormone (thyroxine) and higher than normal levels of another hormone (thyroid
stimulating hormone; TSH). SCH has been shown to be a risk factor for adverse pregnancy outcomes such
as miscarriage and pre-term birth, however there is disagreement over what is defined as SCH.It remains unknown whether mildly raised levels of TSH (2.5-4.0mIUL) are linked to adverse fertility and
pregnancy outcomes. Despite this, international societies recommend that for women who are considered
“high risk” such as those with a history of subfertility or miscarriage, a lower level of TSH should be
achieved before getting pregnant (TSH <2.5mIU/L) and this is through initiating a treatment called
levothyroxine. It is unknown whether this management strategy is beneficial. In addition, screening data from the TABLET (Thyroid AntiBodies and LEvoThyroxine) trial has shown that up-to 20% of women will have mildly raised TSH levels (>2.5mIU/L). This is a significant proportion of the population.The aim of this study is to explore the fertility and pregnancy outcomes for women who had their thyroid
function tested preconception. We wish to define SCH using an accurate cut-off which clinicians can apply
when diagnosing women pre-pregnancy. Finally, we want to investigate whether levothyroxine treatment had
any effect on outcomes. This will be the first study to use pre-pregnancy thyroid data and will form the
foundation for a clinical trial on the subject.REC name
West Midlands - Black Country Research Ethics Committee
REC reference
20/WM/0257
Date of REC Opinion
31 Mar 2021
REC opinion
Further Information Favourable Opinion