Anti-Müllerian Hormone Level Determinants among Non-Polycystic-Ovary-Syndrome Women Undergoing In Vitro Fertilization: A Retrospective Cross-Sectional Study

Background and Objectives: The anti-Müllerian hormone (AMH) is a crucial biomarker in regulating ovarian follicle development and female fertility. AMH levels predict ovarian responses in in vitro fertilization (IVF) cycles, helping clinicians tailor treatment strategies. This study aims to determine whether thyroid autoimmunity, age, body mass index (BMI), sexual hormone levels, and 25-hydroxyvitamin D levels influence serum AMH in non-polycystic-ovary-syndrome (PCOS) euthyroid women. Materials and Methods: This retrospective cross-sectional study examined 52 female patients at Zygota Fertility Clinic between 2018 and 2022. Women aged 20–45 years with regular menstrual cycles were included, while conditions such as abnormal thyroid-stimulating hormone (TSH) levels, PCOS, and systemic autoimmune diseases were excluded. A number of parameters were measured in the study, including the subjects’ age, BMI, 25-hydroxyvitamin D, serum free thyroxine (fT4), TSH, various antibodies, and a range of reproductive hormones. An analysis of the relationships between AMH and other variables was conducted using Spearman’s correlation coefficient, and an assessment of the impact of confounding factors on AMH levels was conducted using a multivariable linear regression model. Results: The results revealed significant negative correlations between AMH levels and age (rho: −0.484, p < 0.001) and follicle-stimulating hormone (FSH) (rho: −0.550, p < 0.001), while positive correlations existed between AMH and estradiol (rho: 0.352, p = 0.011) and total testosterone (rho: 0.542, p < 0.001). No significant correlations were found between AMH levels and BMI, LH, or 25-hydroxyvitamin D. Conclusions: In this study, ovarian reserve was influenced by age, estradiol, and total testosterone in non-PCOS euthyroid women undergoing IVF. Conversely, BMI and vitamin D status did not significantly impact AMH levels. In order to better understand and possibly manage ovarian reserve, a holistic approach is absolutely essential, taking into account age, weight, hormonal balance, nutrition, and thyroid health.