The relationship between thyroid autoimmunity and poor response to ovarian stimulation in in vitro fertilization...

Thyroid autoimmunity (TAI) is the most common autoimmune disorder. Patients with TAI are usually euthyroid, and the presence of anti-thyroid peroxidase (anti-TPO) in patients with or without thyroid dysfunction is associated with infertility, recurrent embryo implantation failure, and early pregnancy loss. We aimed to investigate the relationship between low ovarian reserve, pregnancy outcomes, and TAI.

This retrospective cohort study was conducted in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients between 2010 and 2018. All patients (n = 1400) for whom thyroid autoantibody testing was requested were detected. A study group was formed from patients with anti-TPO positivity (n = 363). The control group (n = 555) comprised euthyroid anti-TPO negative patients matched to the study group regarding age and body mass index (BMI).

Mean serum TSH value was 2.35 ± 1.70 mIU/mL in anti-TPO-positive patients and 1.81 ± 1.2 mIU/mL in controls, and the difference was significant (p < 0.05). Total dose of gonadotropins used in ovulation induction in anti-TPO-positive and control patients were 3000 IU and 2700 IU, respectively, and the difference was statistically significant (p < 0.05). The number of metaphase 2 oocytes was significantly lower in the anti-TPO-positive group (p < 0.05). Embryo transfer number and embryo grade were significantly lower in the anti-TPO-positive group (p < 0.01). Poor ovarian response was significantly higher in anti-TPO-positive patients (40%) as compared to anti-TPO-negative controls (30%) (p < 0.01). Clinical pregnancy rate was significantly lower in the anti-TPO-positive group (29.2%), as compared to the antibody-negative group (38.4%) (p < 0.01).

There are controversial data regarding the impact of antithyroid antibodies on ovarian reserve and pregnancy outcome after IVF treatment. The results of this study indicate that there was a relationship between TAI and poor ovarian response, and that TAI adversely affects IVF outcomes. Further investigations are required to explore the mechanism behind these effects.