Prolonged follicle stimulation decreases pregnancy rates after in vitro fertilization

Abstract

Ovarian stimulation with a GnRH-a and hMG for IVF treatment offers the potential to extend the period of follicle recruitment and growth free of the restriction imposed by a spontaneous midcycle LH surge. A randomized trial investigating the impact of extending follicle growth by 1 day resulted in a significantly reduced PR, despite an increase in the number of larger follicles (greater than or equal to 17 mm) at the time of hCG. The reason for a reduced PR was not related to the number of ova recovered or embryo quality. This suggests that follicular aging or the duration of estrogen rise may be important.