Delaying Thyroxine Until Positive Beta-Human Chorionic Gonadotropin is Safe for Patients Receiving Fertility Therapy: Applying New ATA Guidelines to Subclinical Hypothyroidism

Abstract Objective This study sought to examine the effect of changing TSH threshold recommendations from 2.5 to 4 mIU/L before fertility therapy on the prevalence of early gestational subclinical hypothyroidism (SCH) (TSH2 >2.5 mIU/L) and to evaluate implications on progression to clinical pregnancy (defined as detection of cardiac activity on ultrasound). Methods A retrospective chart review was performed in an academic fertility clinic on all patients with a measured pre-treatment TSH (TSH1) and positive beta-human chorionic gonadotropin following fertility treatment. The study assessed the effect of TSH2 on ongoing pregnancy, both in patients newly diagnosed with SCH and in patients previously receiving LT4, stratified by initial TSH. Results Of 482 women included in the study, baseline TSH (TSH1) was Conclusion Rate of progression to clinical pregnancy was equivalent between women with an early pregnancy TSH (TSH2)