Thyroid autoantibodies are not associated with recurrent pregnancy loss

Approximately 1% of all women have recurrent pregnancy loss, defined as >/=3 spontaneous losses of pregnancy; however, a cause is determined in only 50% of cases. Recent studies have associated the presence of thyroid autoantibodies during the first trimester of pregnancy with spontaneous abortion in the current pregnancy among women without a history of recurrent abortion. The objective of this study was to determine whether circulating thyroid autoantibodies were associated with recurrent pregnancy loss.

Sera from 74 nonpregnant women with a history of recurrent pregnancy loss and from 75 healthy, fertile control subjects of similar gravidity were tested for thyroglobulin and thyroid peroxidase antibodies by means of radioimmunoassay kits. All women had a third-generation thyroid-stimulating hormone assay performed. Samples were obtained >/=6 months after a pregnancy.

Twenty-two of the women with a history of recurrent pregnancy loss (29.3%) and twenty-eight of the control subjects (37%) had positive results for either one or both of the thyroid autoantibodies (P >. 05). Mean thyroid-stimulating hormone levels and the proportion of women with abnormal thyroid-stimulating hormone values did not differ between the 2 groups.

Women with a history of recurrent pregnancy loss are no more likely than are fertile control subjects to have circulating thyroid autoantibodies. Testing for antithyroid antibodies is not clinically useful in the evaluation of patients with a history of recurrent pregnancy loss.