Multiple follicles in IVF stimulation cycles lead to high estradiol levels, high estradiol levels in turn lead to LH surge which triggers ovulation and rise in serum progesterone levels. Premature ovulation of premature progesterone rise in turn defeats the purpose of ovulation induction. Hence in order to supress this premature LH surge, GnRH agonists and antagonist are administered until the day of trigger.
