Tehran Thyroid and Pregnancy Study: Objectives and Study Protocol

Thyroid dysfunction is the second most common endocrine disease in women of reproductive age. Controversial data on the adverse effect of subclinical thyroid dysfunctions and adverse feto-maternal outcomes.. This study aims to identify the prevalence of thyroid dysfunction during pregnancy and to assess the effectiveness of treatment with levothyroxine on pregnancy outcomes in Tehranian women with thyroid autoimmunity with or without subclinical thyroid dysfunction..Patients and This study encompasses two phases: 1- A population based cross sectional study using a cluster sampling method that screens first trimester pregnant women for thyroid disorders, 2- A double-blind randomized clinical trial to determine the effectiveness of levothyroxine on adverse pregnancy outcomes in women with thyroid autoimmunity with or without subclinical thyroid dysfunction. Pregnant women will be assessed at their first prenatal visit for serum TSH, T4, T-uptake, TPOAb and urinary iodine following which they will be classified as: 1- Normal, 2- Subclinical TPOAb negative and 3- Subclinical/euthyroid TPOAb positive. Women in groups two and three will be randomly divided into two groups: Group A will be treated with levothyroxine (LT4), and group B will not receive any treatment. All study participants will be followed and rates of adverse pregnancy outcomes in the treated and untreated groups will be measured.. Results of the study will provide reliable information regarding the prevalence of thyroid dysfunction among Tehranian women using universal thyroid screening, along with identification of the iodine status of their community. We aim to determine whether LT4 treatment exerts beneficial effects in women without overt thyroid dysfunction..