Different stimulation protocols have been offered for PCOS patients undergoing ARTs : GnRH agonist and GnRH antagonist protocols. There is no clear evidence for the advantage of one over the other. The GnRH agonist was initially considered to be the protocol of choice in PCOS women. Due to increased risk of mid-cycle gonadotrophin flares, multiple pregnancies and OHSS its usage has been restricted to certain situation. GnRH antagonist has been shown to have an advantage over the agonist in form of quicker onset of action, short duration of treatment, lesser total dose of gonadotropins required, lower cost, better to be tolerated, lower incidence of LH surge, lower incidence of OHSS and being more patient friendly. Recent data have been obtained from systematic review and meta analysis studies were showed no significant difference in fertilization rate and pregnancy outcome when comparing the two GnRH analogues; agonist versus antagonist in PCOS and normal women. However another study showed higher clinical pregnancy when ultra-long agonist was used instead of long agonist protocol.

The aim of every IVF/ICSI program is to achieve multi-follicular development and collection of several appropriately matured oocytes without causing OHSS and with a comparable pregnancy rate. This is especially important in women with PCOS as they usually exhibit greater sensitivity to exogenous gonadotropin stimulation than women with normal ovaries.