Objective: To evaluate the effect of endogenous luteinizing hormone level in the middle of in vitro fertilization cycle with depot GnRH agonist on the outcomes of assisted reproduction. Design: Prospective clinical trial. Setting: 2nd Department of Gynecology and Obstetrics of Medical Faculty and L. Pasteur University Hospital Košice Methods: In the prospective clinical trial the effect of endogenous LH level during ovarian hyperstimulation with recombinant follicle stimulating hormone on outcomes of IVF was evaluated. The total number of 364 in vitro fertilization cycles in normogonadotrophic women undergoing assisted reproduction with GnRH agonist down-regulation and recombinant FSH controlled ovarian stimulation were included. A part of cycles with low residual LH levels were not included into statistical analysis, because of stimulation protocol adaptation. 315 cycles were taken into final statistical analysis. These cycles were divided into three groups according to middle stimulation LH level: under 0.5 IU/L, 0.5–2.0 IU/L and over 2.0 IU/L. Results: The best results were achieved in the middle group. The differences in most of parameters were statistically significant: FSH dosage, days of stimulation, number of oocytes, estradiol level, number of embryos and fertilization rate. Pregnancy rate and early pregnancy loss differences were not significant. Conclusions: It was statistically evaluated that the best outcomes of assisted reproduction were in the group with LH level 0.5–2.0 IU/L. Correlation lines proved that the LH level 0.5 IU/L is the point under that the outcomes can worsen. It can be explained that the differences between pregnancy rates were not significant, because of low number of cycles with low residual LH levels included.

        Key words: IVF, luteinizing hormone, controlled ovarian stimulation