Table 1.

Advantages and disadvantages of the major IVM protocols

	Advantages	Disadvantages
Standard IVM	• Simple one-step culture system [8, 18] • All oocytes at the same immature meiotic stage at the start of culture [8, 41]	• Relatively low MII rates at ~ 50% [41–43] • Modest embryo yield and live birth rates [41, 43, 44]
Biphasic IVM	• Relatively high MII rates at ~ 70% [22] • Good embryo yield and live birth rates [22, 23, 43]	• Additional laboratory burden due the extra day of culture [22] • Has only recently been introduced in a limited number of IVM labs [23, 45]
hCG-primed IVM	• Relatively high MII rates at ~ 70% [46]	• Oocytes are collected at a mixture of meiotic stages [47] • Additional laboratory burden due to at least two rounds of ICSI per OPU [18] • IVM of GVB oocyte cohort is suboptimal as the exact extent of their meiotic progression at start cannot be determined [47] • Modest live birth rates [41, 47] • Prohibitive to the use of any pre-IVM culture approach [34]
Rescue IVM	• GV oocytes are common in conventional IVF patients • May generate additional embryos for transfer [38]	• Oocytes commonly have meiotic defects [48] • IVM in the absence of cumulus cell support → poor oocyte quality [20, 27, 40] • Questionable safety [39, 40]