Mild thyroid dysfunction affects one in five women with a history of miscarriage or subfertility

Mild thyroid abnormalities affect up to one in five women with a history of miscarriage or subfertility which is a prolonged time span of trying to become pregnant, according to a new study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.

Thyroid disorders are common in women of reproductive age. Although the prevalence of thyroid disorders in pregnancy are well understood, little is known about how common these disorders are in women prior to pregnancy. Detecting thyroid disorders before a woman becomes pregnant is essential because thyroid abnormalities can have negative effects such as reduced fertility, miscarriage and pre-term birth.

“This study has found that mild thyroid abnormalities affect up to one in five women who have a history of miscarriage or subfertility and are trying for a pregnancy,” said Rima Dhillon-Smith, M.B.Ch.B., Ph.D., of the University of Birmingham and the Birmingham Women's and Children's NHS Foundation Trust in Birmingham, U.K. “It is important to establish whether treatment of mild thyroid abnormalities can improve pregnancy outcomes, given the high proportion of women who could potentially be affected.”

This study was conducted across 49 hospitals in the U.K. over five years. The researchers studied over 19,000 women with a history of miscarriage or subfertility who were tested for thyroid function. They found up to one in five women had mild thyroid dysfunction, especially those with an elevated BMI and of Asian ethnicity, but overt thyroid disease was rare. Women who suffered multiple miscarriages were no more likely to have thyroid abnormalities compared to women who have conceived naturally with a history of one miscarriage.

Other authors include: Aurelio Tobias, Lee J. Middleton, Kirandeep K. Sunner, Samantha Farrell-Carver and Kristien Boelaert of the University of Birmingham; Paul P. Smith, Justin J. Chu, Mark D. Kilby and ArriCoomarasamy of the University of Birmingham and the Birmingham Women's and Children's NHS Foundation Trust; Krystyna Baker of the University of Oxford in Oxford, U.K.; Ruth Bender-Atik of the Miscarriage Association in Wakefield, U.K.; Rina Agrawal, Tarek Ghobara and Siobhan Quenby of the University Hospitals Coventry & Warwickshire NHS Trust in Coventry, U.K.; Kalsang Bhatia of the East Lancashire Hospitals NHS Trust in Lancashire, U.K.; Edmond Edi-Osagie of the Central Manchester University Hospital Foundation Trust in Manchester, U.K.; Ayman Ewies and Rachel Small of the City Hospital in Birmingham, U.K.; Pratima Gupta of the University Hospital Birmingham in Birmingham, U.K.;Davor Jurkovic of the University College Hospitals NHS Foundation Trust in London, U.K.; Yacoub Khalaf of the Guy’s and St Thomas’ NHS Foundation Trust in London, U.K.; Khashia Mulbagal of the Bolton NHS Foundation Trust in Bolton, U.K.; Natalie Nunes of the Chelsea and Westminster NHS Foundation Trust in London, U.K.; Caroline Overton of the University Hospitals Bristol NHS Foundation Trust in Bristol, U.K.; Raj Rai of the Imperial College Healthcare NHS Trust in London, U.K.; Nick Raine-Fenning of the Nottingham University Hospitals NHS Trust in Nottingham, U.K.; Lynne Robinson of the Birmingham Women’s and Children’s Foundation Trust; Jackie Ross of the King’s College Hospital NHS Foundation Trust in London, U.K.; Andrew Sizer and Martyn Underwood of the Shrewsbury and Telford NHS Trust in Shrewsbury, U.K.; Jane Daniels of the Queens Medical Centre in Nottingham, U.K.; Shakila Thangaratinam of the Queen Mary University of London in London, U.K.; and Shiao Chan of the National University of Singapore in Singapore.

The study received funding from the Efficacy and Mechanism Evaluation Programme.

The manuscript, “The Prevalence of Thyroid Dysfunction and Autoimmunity in Women with History of Miscarriage or Subfertility,”was published online, ahead of print.