Spontaneous luteinizing hormone (LH) surges are associated with more rapidly increasing estradiol (E2) and follicle stimulating hormone (FSH) in in vitro fertilization and embryo transfer

In a retrospective analysis of 64 patients stimulated with human menopausal gonadotropin (hMG) and/or pure follicle stimulating hormone (FSH); 35 cycles with spontaneous luteinizing hormone (LH) surges were compared with 29 control cycles with respect to serum FSH and estradiol (E2) levels drawn on the day prior to and the day of human chorionic gonadotropin (hCG), approximately 16 hr after gonadotropin stimulation. FSH decreased significantly (P<0.05) in control cycles where two or more preovulatory oocytes (preovs) were obtained, in contrast to cycles with a spontaneous LH surge, where FSH increased irrespective of the number of preovs. The E2 increase in the LH surge cycles was significantly higher (P<0.05) than in the control cycles. However, the increase in E2 did not correlate with the change in FSH levels or with the number of preovs.