Synchronization of endogenous and exogenous FSH stimuli in controlled ovarian hyperstimulation (COH)

We have previously observed that exogenous oestradiol can delay theintercycle increase in plasma follicle stimulating hormone (FSH). Theincrease in plasma FSH that follows discontinuation of exogenous oestradiolpeaks after 3 days. We have now studied the possibility of using exogenousoestradiol to synchronize the increase in endogenous FSH with the onset ofhuman menopausal gonadotrophin (HMG) treatment in controlled ovarianhyperstimulation (COH). A total of 30 women aged 35.1+/-6.3 years(mean+/-SD) undergoing ovarian stimulation received 2 mg of oestradiolvalerate twice daily starting on day 25 of the previous menstrual cycleuntil the first Tuesday following menses. Ovarian stimulation was initiated3 days later. On the last day of oestradiol treatment, plasma oestradiol,FSH and luteinizing hormone (LH) (mean+/-SEM) were 566+/-53 (pmol/l),3.8+/-0.4 (IU/l) and 5.5+/- 0.8 (IU/l) respectively. After 3 days, the FSHand LH (mean+/-SEM) had increased to 6.7+/-0.7 and 6.9+/-0.7 (IU/l)respectively while oestradiol decreased to 251+/-29 (pmol/l). The meannumber (+/-SEM) of HMG ampoules used was 25.1+/-2.7 and treatment lasted11.3+/-0.9 days. Five women became pregnant for a pregnancy rate (ongoing)of 19 (15)%. If all women aged >40 years (six women who did not becomepregnant) were excluded from analysis the pregnancy rate (ongoing) was 24(19%). These results indicate that exogenous oestradiol can safely be usedfor the synchronization of endogenous and exogenous FSH stimuli in COH.This approach provides the practical advantage of permitting an advancedtiming of the onset of COH treatments when gonadotrophin- releasing hormone(GnRH) agonists are not used, which improves treatment convenience forpatients and team members alike. Further development of this model mayenable control of the onset of natural cycles which may find practicalapplications for timing assisted reproductive techniques (intrauterineinsemination or in-vitro fertilization) in the natural cycle.