Subclinical Autoimmune Thyroid Dysfunction in Infertile Euthyroid Patients: The Risk of Spontaneous Abortion

OBJECTIVE: To investigate whether in vitro fertilization (IVF) procedures in patients with autoimmune thyroid disorder increase the likelihood of conception and delivery. STUDY DESIGN: The study included 125 patients (N=241 with male factor cases included) who were treated for infertility at the tertiary center between 2009 and 2015, either conservatively or by IVF. In all the participants, thyroid function was assessed by measuring serum concentrations of thyroid- stimulating hormone, free thyroxine, and free triiodothyronine, whereas thyroid autoimmunity was assessed by measuring thyroid peroxidase antibodies and thyroglobulin antibodies (TgAb) in the serum samples, and by thyroid ultrasound examinations. The reproductive outcomes were compared between the infertile patients with autoimmune thyroid disorder and patients with normal hormone levels, negative thyroid antibody tests, and normal ultrasound findings. RESULTS: In the group of patients with autoimmune thyroid disorder who were treated by IVF, significantly more women conceived. Also, significantly more women in this group had spontaneous abortions as compared to the women with euthyroid (p=0.039). The number of births per woman did not differ significantly between the groups. The percentage of births (birth per patient) was similar and without significant statistical difference. Similar results were observed in patients with autoimmune thyroid disorders and combined infertility (female- male). CONCLUSION: IVF procedures significantly increase the likelihood of conception in patients with subclinical autoimmune thyroid disorder, but not the likelihood of delivery. Despite the euthyroid status as a result of levothyroxine replacement, the risk of spontaneous abortion was increased in patients with autoimmune thyroid disorder, regardless of the type of infertility treatment (conservative or IVF)