Evaluation of the impact of levothyroxine treatment on the psychomotor developmental status of three-year-old children born to mothers with mild thyroid impairment; Tehran Thyroid and pregnancy study: study protocol for a randomized clinical trial

BACKGROUND: Despite the known adverse effects of maternal overt hypothyroidism on the neurocognitive development of children, there is uncertainty regarding the impact of gestational thyroid dysfunction or autoimmune thyroiditis on infant/child neurological development. This study aims to evaluate the impact of levothyroxine (LT4) treatment on the psychomotor developmental status of three-year-old children born to mothers with mild thyroid impairment (subclinical hypothyroidismwith/without autoimmune thyroiditis). METHODS/DESIGN: This is a follow-up study of the Tehran Thyroid and Pregnancy Study, a randomized trial in which subclinical hypothyroid pregnant women were assigned to an intervention group (treated with levothyroxine) or a control group (received no treatment). The primary outcome for the purpose of the present study is the developmental status of the children, aged three years, in five domains (communication, gross motor, fine motor, problem-solving, and social–personal domains) using the Ages and Stages Questionnaire (ASQ). DISCUSSION: The study is designed to assess the developmental status of children born to mothers with mild thyroid impairment (subclinical hypothyroidism with/without autoimmune thyroiditis). This study is one of the limited studies available in this field and has the potential to facilitate much-needed information for related public health policies. TRIAL REGISTRATION: Iranian Registry of Clinical Trials, IRCT2017090314849N5. Registered on 11 September 2017. Iranian Registry of Clinical Trials, IRCT2017090414849N6. Registered on 14 October 2017. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-018-3130-5) contains supplementary material, which is available to authorized users.