Relationship of thyroid hormone levels and thyroid autoantibodies with early pregnancy loss and infertility

Prevalence of abnormalities in thyroid hormones and thyroid autoantibodies in patients with a history of early pregnancy loss (EPL) (n = 17) and unexplained infertility (UI) (n = 25), were compared with that of 45 control patients. TSH, antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-TG) antibody levels in UI and EPL groups were similar to that of the control group. TSH was normal in 39, 22 and 13 of control, UI and EPL patients, respectively. Among patients with a normal TSH, fT4 was higher (p < 0.001) and fT3 was lower (p < 0.001) in infertile patients when compared with the control group. Thyroid function tests seem to be associated with infertility but their association with EPL is weaker. Infertility seems to be associated with a high fT4 and low fT3 status. Thyroid autoantibodies do not seem to be associated with either infertility or EPL.