Impacts of thyroid stimulating hormone and thyroid peroxidase antibody on pregnancy outcomes of in vitro fertilization-embryo transfer

Objective: To investigate the effects of thyroid stimulating hormone (TSH) and thyroid peroxidase antibody(TPOAb) on pregnancy outcomes of in vitro fertilization-embryo transfer (IVF-ET). Methods: The patients who underwent IVF-ET at the Reproductive Medicine Center of Hefei Maternal and Child Health Care Hospital from December 2019 to November 2023, and had normal free thyroxine and 0.3-<10 mIU/L TSH levels were selected as subjects. The patients were divided into three groups based on TSH levels: 0.3-<2.5 mIU/L, 2.5-4 mIU/L, and >4-<10 mIU/L, and the patients with normal free thyroxine and TSH levels were further divided into TPOAb-positive and TPOAb-negative groups. The biochemical pregnancy rate, clinical pregnancy rate and miscarriage rate were compared among patients with different TSH and TPOAb groups. Results: A total of 3 876 patients were recruited, including 830 patients with fresh embryo transfer cycles and 3 046 patients with frozen-thawed embryo transfer cycles. In the patients with fresh embryo transfer cycles, the biochemical pregnancy rate, clinical pregnancy rate and miscarriage rate were 59.16%, 52.77% and 19.41%, respectively. In the patients with frozen-thawed embryo transfer cycles, these rates were 55.52%, 46.98% and 20.27%, respectively. For both groups, there were no statistically significant differences in biochemical pregnancy rate, clinical pregnancy rate and miscarriage rate between TPOAb-positive and TPOAb-negative patients or among the patients with different TSH groups (all P>0.05). Additionally, a follow-up study of 150 patients who had successfully delivered after IVF-ET from 2020 to 2022 with TSH levels of >4-<10 mIU/L showed that no intellectual developmental issues or tendencies toward intellectual developmental disorders were found in their offsprings. Conclusion: In the context of normal free thyroxine levels, this study did not find any impacts of mildly elevated TSH levels or isolated TPOAb positivity on the pregnancy outcomes of IVF-ET.