The role of thrombophilia and thyroid autoimmunity in unexplained infertility, implantation failure and recurrent spontaneous abortion.

BACKGROUND The role of thrombophilia and thyroid autoimmunity in unexplained infertility (UI), implantation failure (IF) and recurrent spontaneous abortion (RSA) is controversial and poorly understood. METHODS From March, 2004 to January, 2007, 119 women were prospectively included: 32 oocyte donors, 31 patients with UI, 26 with IF and 30 with RSA. The IF and RSA groups presented normal preimplantation genetic screening. Protein C, protein S, antithrombin III, lupus anticoagulant, activated protein C resistance (APCR), immunoglobulin M and G anticardiolipin antibodies, homocystine, Factor V Leiden, prothrombin G20210A mutation, methylentetrahydrofolate reductase C677T mutation, thyroid-stimulating hormone (TSH), free thyroxine, anti-thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies were assessed. RESULTS The prevalence of thrombophilia was high and similar among groups. In the IF group, the prevalence of APCR (15.4%), lupus anticoagulant (11.5%) and combined thrombophilia (19.2%) was higher, but not significantly different, than the other three groups. The prevalence of thyroid autoimmunity in women with IF (anti-TPO antibodies, P = 0.009; anti-TPO plus anti-TG antibodies,P = 0.04) and UI (anti-TPO, P = 0.002; anti-TG, P = 0.019; anti-TPO plus anti-TG antibodies, P = 0.005) was significantly increased in comparison to those with RSA. There was also a trend towards a higher prevalence of thyroid autoimmunity in the UI and IF groups than in the control group. TSH and free thyroxine levels all remained within a normal range. CONCLUSIONS When embryo aneuploidy is ruled out, thrombophilia could constitute an etiologic factor in IF. Furthermore, thyroid autoimmunity is strongly related to UI and IF.