We explored the effects of different doses of letrozole on the incidence of ovarian hyperstimulation syndrome (OHSS) after oocyte retrieval during in vitro fertilization (IVF) in patients with high-risk OHSS. A total of 88 patients were randomly divided into a control group, and groups treated with 2.5 mg, 5 mg, or 7.5 mg of letrozole. We found that from the fifth day after human chorionic gonadotrophin (hCG) treatment, the E2 level decreased and there were statistical differences between the four groups (p < 0.05). From the eighth day after hCG treatment, the luteinizing hormone (LH) level increased, but the progesterone (P) level decreased. There were statistical differences between groups (p < 0.05). From the fifth day after hCG treatment, the level of vascular endothelial growth factor (VEGF) increased in the control, but decreased in the letrozole groups in a dose-dependent manner. There were statistically significant differences between groups (p < 0.001). The incidence of moderate and severe OHSS was lower in the 7.5 mg group than in the control group (p < 0.05). In the patients with high-risk OHSS undergoing whole embryo frozen transfer, treatment with 7.5 mg letrozole may be useful to limit OHSS.
Keywords: In vitro fertilization; luteal phase; ovarian hyperstimulation syndrome.