Positive effects of thyroid replacement therapy on assisted reproductive technology outcomes in women with subclinical hypothyroidism with positive thyroid peroxidase autoantibodies.

Objective: To study the beneficial effects of thyroid replacement therapy (TRT) on pregnancy outcomes in patients with subclinical hypothyroidism (SCl hypoT) with respect to thyroid peroxidase (TPO) autoantibodies.

Design: Retrospective study of 706 patients.

Setting: Not applicable.

Patients: The study evaluated 706 patients, who were divided into 3 cohorts: euthyroid patients, with pre-in vitro fertilization thyroid-stimulating hormone levels of <2.5 μIU/mL; patients with SCl hypoT, defined as thyroid-stimulating hormone levels of >2.5 μIU/mL and <4 μIU/mL, who were not treated; and patients with SCl hypoT who received TRT. The 3 cohorts were further subclassified into 2 groups, each based on TPO antibody levels.

Interventions: The cohorts were compared for the effects of TRT on pregnancy outcomes.

Main Outcome Measures: Identification of effects of TRT on assisted reproductive technology outcomes.

Results: Patients with SCl hypoT had significantly fewer positive pregnancy outcomes than euthyroid patients. Importantly, low-dose TRT was found to be beneficial in improving IVF success and pregnancy outcomes in patients with SCl hypoT. The original cohort of patients, further classified into 2 subgroups on the basis of antithyroid (TPO) antibodies, showed that low-dose TRT was associated with improved pregnancy outcomes in women with SCl hypoT and TPO-positive antibodies.

Conclusions: Our findings demonstrate that low-dose TRT may be beneficial in improving in vitro fertilization success and pregnancy outcomes in women with SCl hypoT and TPO-positive antibodies.