Association between TSH Level and Pregnancy Outcomes in Euthyroid Women Undergoing IVF/ICSI: A Retrospective Study and Meta-analysis

The aim of this study was to determine the association between thyroid-stimulating hormone (TSH) level and pregnancy outcomes in euthyroid women undergoing in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI). A total of 1185 women were enrolled in the retrospective study, and 12 studies with a total of 6624 women were included in the meta-analysis (including the data of the present retrospective study). Participants in the retrospective study were divided into two groups in terms of their serum TSH levels: TSH <= 2.5 mIU/L group (n=830) and TSH >2.5 mIU/L group (n=355). They were monitored for the status of clinical pregnancy or miscarriage. In the TSH <= 2.5 mIU/L group, 441 (53.1%) women achieved clinical pregnancy, while 48 (5.8%) had early pregnancy loss and 12 (1.4%) had ectopic pregnancy. In the TSH >2.5 mIU/L group, 175 (49.3%) women achieved clinical pregnancy, while 21 (5.9%) had early pregnancy loss and 3 (0.8%) had ectopic pregnancy. No significant differences were observed between the two groups in pregnancy outcomes (P=0.126, P=0.512, P=0.297). The meta-analysis also revealed no significant difference in the clinical pregnancy rate and the miscarriage rate between women with serum TSH <= 2.5 mIU/L and those with serum TSH >2.5 mIU/L. In conclusion, high TSH levels (TSH level >2.5 mIU/L) did not affect clinical pregnancy rate or increase miscarriage rate in euthyroid women undergoing IVF/ICSI.