Thyroid‐stimulating hormone level is negatively associated with fertilization rate in patients with polycystic ovary syndrome undergoing in vitro fertilization

Objective In this study, we investigated the effect of thyroid-stimulating hormone (TSH) level on the outcomes of in vitro fertilization (IVF) in patients with polycystic ovary syndrome (PCOS). Methods Data pertaining to 60 patients who underwent IVF between May 2017 and May 2018 were included in the study. Thirty-two patients were diagnosed as PCOS (PCOS group) and 28 patients had tubal infertility (control group). Serum and follicular fluid TSH levels and follicular cyclic AMP (cAMP) level were detected by ELISA. TSH receptor (TSHR) expression level in granulosa cells was quantified by RT-PCR and Western blot. Results In the PCOS group, oocyte maturation rate and fertilization rate were significantly lower than in the control group. Serum and follicular fluid TSH levels and ovarian cAMP level were higher in the PCOS group with an upregulation of ovarian TSHR. On multivariate linear regression analysis, fertilization rate showed a negative correlation with TSH levels in serum (B = -0.106, P = 0.005) and follicular fluid (B = -0.107, P = 0.001). Conclusion In PCOS patients, TSH levels, both in serum and follicular fluid, were negatively correlated with IVF oocyte maturation rate and fertilization rate. The effect of TSH on controlled ovarian hyperstimulated oocyte growth was likely mediated by the TSHR/cAMP signaling pathway.