Numerous studies have focused on association of TAI, infertility and obstetrical complications[6C9]. Results There were no significant differences between the groups regarding mean levels of FF TSH and FF fT4. Statistically significant correlation was discovered regarding the levels of serum and FF TPOAbs (0,961, p 0.001 in TAI positive, 0,438, p = 0.025 in TAI negative group) and TgAbs (0,945, p 0.001 in TAI positive, 0,554, p = 0.003 in TAI negative SC 57461A group). Pregnancies rates per initiated cycle and per embryotransfer cycle were significantly different between TAI positive and TAI negative group, (30.8% 61.5%), p = 0.026 and (34.8% 66.7%), p = 0.029, respectively. Multivariate analysis showed that TAI positive women had less chance to achieve pregnancy (p = 0.004, OR = 0.036, 95% CI 0.004C0.347). Conclusions Higher levels of thyroid autoantibodies in FF of TAI positive women are strongly correlated with serum levels and may have effect on the post-implantation embryo development. Introduction Thyroid autoimmunity (TAI) is the most prevalent autoimmune disease in women of reproductive age, affecting 5%-20% of female population . Hashimoto thyroiditis (HT) is the most common clinical presentations of TAI, characterized by the presence of thyroid autoantibodies, including thyroid peroxidase antibodies (TPOAbs) and thyroglobulin antibodies (TgAbs) , mediating antibody-dependent cell-mediated cytotoxicity [3C5]. Numerous studies have focused on association of TAI, infertility and obstetrical complications[6C9]. The hypotheses have been suggested to explain possible connection between TAI and obstetrical complications. In the first one, TAI is considered to be a consequence of general autoimmune response, explaining higher rate of fetal graft rejection . The second hypothesis implies that TAI could be associated with thyroid hormones deficiency, or inability of thyroid gland to adapt to hormonal changes during pregnancy . TAI is also associated with an increased risk of unexplained subfertility . It was suggested that thyroid autoantibodies may serve as independent markers of assisted reproductive technology (ART) outcome failure . The risk for miscarriage may be higher in euthyroid, subfertile women with TAI undergoing ART , with lower pregnancy rate  compared with subfertile women without TAI. Controlled ovarian stimulation, as a part of ART procedure, seems to have a long-term impact on TSH levels , leading to a significant increase of serum TSH in the very first period of pregnancy and alter thyroid function in euthyroid TAI positive patients . Follicular fluid (FF) provides an important microenvironment for oocytes maturation and development . Monteleone et al, verified the presence of thyroid autoantibodies in FF of TAI positive women, suggesting that these antibodies could cross the follicule-blood barrier and damage maturing oocytes used in ART procedure, due to antibody mediated cytotoxicity . The objective of the study was to assess the association of the levels of thyroid autoantibodies in FF and ART outcome expressed as the achieved pregnancies. Subjects and methods This prospective study was conducted during the period from November 2014 to July 2016, in the Clinic for Gynecology and Obstetrics “Narodni front”, Belgrade, Serbia. We enrolled 26 euthyroid subjects with TAI undergoing ART, and 27 euthyroid age and body mass index (BMI) matched TAI negative subjects undergoing ART (one of these subjects has withdrawn consent during the later course of the study). Ethical approval The ethical committee of the Faculty of Medicine, University of Belgrade and the ethical committee of Clinic for Gynecology and Obstetrics “Narodni front”, granted approval for SC 57461A the present study and written informed consents were obtained Rabbit Polyclonal to PEK/PERK SC 57461A from all subjects. Study population criteria ART procedure inclusion criteria were predefined by the National Expert Commission of the Ministry of Health for biomedical assisted fertilization procedures . Inclusion criteria for ART: couples in whom other possibilities for infertility treatment have been exhausted, women with infertility despite appropriate treatment, women up to age 40 years, with preserved ovarian function, with BMI 30 kg/m2, all forms of male subfertility with the presence of live or morphologically correct sperm in the ejaculate. Exclusion criteria for ART: anomalies and benign tumors of the uterus, fallopian tubes and ovaries that disable ART procedure, the achieving and development of pregnancy, the existence of a malignant tumor or suspicious malignancy in the uterus, fallopian tubes and ovaries, any diseases that can significantly influence pregnancy or pregnancy outcome, and diseases in which the anesthesia or pregnancy potentially can threaten the mothers life. Clinical methodology Medical history, physical examination and laboratory analyses were performed in each patient and.