Abstract: Autoimmune thyroid disease (AITD) is one of the most common endocrinopathies and is
more prevalent in women. It becomes evident that the circulating antithyroid antibodies that often
follow AITD have effects on many tissues, including ovaries, and therefore that this common
morbidity might have an impact on female fertility, the investigation of which is the aim of the
present research. Ovarian reserve, ovarian response to stimulation and early embryo development
in infertile patients with thyroid autoimmunity were assessed in 45 women with thyroid
autoimmunity and 45 age‐matched control patients undergoing infertility treatment. It was
demonstrated that the presence of anti‐thyroid peroxidase antibodies is associated with lower
serum anti‐Müllerian hormone levels and antral follicle count. Further investigation revealed the
higher prevalence of sub‐optimal response to ovarian stimulation in TAI‐positive women, lower
fertilization rate and lower number of high‐quality embryos in this group of patients. The cut‐off
value for follicular fluid anti‐thyroid peroxidase antibody affecting the above‐mentioned
parameters was determined to be 105.0 IU/mL, highlighting the necessity of closer monitoring in
couples seeking infertility treatment with ART.