Effects of different doses of letrozole on the incidence of early-onset ovarian hyperstimulation syndrome after oocyte retrieval.

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.