Impact of mildly evaluated thyroid-stimulating hormone levels on in vitro fertilization or intracytoplasmic sperm injection outcomes in women with the first fresh embryo transfer: a large study from China

Purpose This study aimed to investigate the association between mild elevation of thyroid-stimulating hormone (TSH) levels and pregnancy outcomes of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatments in women with the first fresh embryo transfer. Methods Large single-center retrospective cohort study of 15,728 patients from January 2018 to December 2022 were enrolled in the analyses. Clinical pregnancy rates, live birth rates, miscarriage rates, and ectopic pregnancy rates were compared between the TSH levels < 2.5 mIU/L group ( N = 10,932) and TSH levels ≥ 2.5 mIU/L group ( N = 4796). Subgroup analysis was performed for patients with TSH levels ≥ 2.5 mIU/L, dividing them into the thyroid peroxidase antibody (TPO)–negative group ( N = 4524) and the TPO-positive group ( N = 272). Results There were no significant differences in the aforementioned pregnancy outcomes between the TSH levels < 2.5 mIU/L group and TSH levels ≥ 2.5 mIU/L group. Similarly, no significant differences were observed in the pregnancy outcomes between the TPO-negative group and the TPO-positive group. Conclusion Mildly elevated pre-conception TSH levels in thyroid-normal infertile patients did not have an impact on pregnancy outcomes of IVF/ICSI treatments.