Influence of Antithyroid Antibodies in Euthyroid Women on In Vitro Fertilization-Embryo Transfer Outcome

PROBLEM: To investigate whether antithyroid antibodies (ATAs) affect the pregnancy outcome in euthyroid women undergoing in vitro fertilization‐embryo transfer (IVF‐ET). METHOD OF STUDY: Thyroid peroxidase antibody (TPOA) and thyroglobulin antibody (TGA) were measured by radioligand assay kits that were used as ATAs in 79 patients with tubal or unexplained infertility who were enrolled in an IVF‐ET program. Women who were positive for antinuclear antibody, lupus anticoagulant, anticardiolipin antibody, and rheumatoid factor were excluded from our study. The study group comprised 28 (29.1%) euthyroid women who were positive for TPOAs, TGAs, or both. Fifty‐one euthyroid women without ATAs served as control subjects. The results were analyzed with linear regression analysis, Student's f‐test, Mann‐Whitney U test, Kruskal‐Wallis analysis of variance, χ2 test, and Fisher's exact test. RESULTS: There were no significant differences between the study group and the control group in patient characteristics such as age, infertility duration, and hormonal profile. There were also no significant differences between the two groups with respect to the number of retrieved oocytes, the fertilization rate, the number of embryos frozen, and the number of embryos transferred. There were no correlations between ATA (TPOA and TGA) titers and the fertilization rate. The clinical pregnancy rate per cycle was significantly lower in the study group, with 26.3% (10/38), compared with 39.3% (35/89) in the control group. The biochemical pregnancy rate per cycle and the miscarriage rate were significantly higher in the study group, 18.4% (7/38) and 40.0% (4/10), respectively, compared with 5.6% (5/89) and 11.4% (4/35), respectively, in the control group. In the study group, both TPOA and TGA titers were significantly higher in the biochemical pregnancy group than in the clinical pregnancy group or the nonpregnancy group. In 10 women with ATAs who achieved pregnancy after IVF‐ET, both TPOA and TGA titers were significantly higher in the miscarriage group than in the ongoing pregnancy/delivery group. CONCLUSION: ATAs in euthyroid women with tubal or unexplained infertility have an association with a poor pregnancy outcome after IVF‐ET treatment.