ABSTRACT
The in vitro maturation (IVM) of human oocytes retrieved from unstimulated ovaries is a reproductive technology of increasing interest. In comparison with controlled ovarian hyperstimulation (COH), the major benefits of IVM treatment include avoidance of the risk of ovarian hyperstimulation syndrome (OHSS), reduced cost, and less complicated treatment. Knowledge regarding the IVM of immature human oocytes and its clinical application has been accumulated during the past couple of years. Fertilization, embryo development and term pregnancies of IVM oocytes have been reported in stimulated cycles,1 natural cycles2 and PCO patients.3 Although some recent studies have shown improved pregnancy rates per embryo transfer,4,5 the pregnancy rate after IVM has in general been low. Likely reasons are suboptimal culture conditions during IVM or inadequate cytoplasmic maturation of the oocyte itself. To overcome these problems, some studies have focused on improved culture media; other studies have tried to optimize the quality of the oocyte by stimulation with oestradiol or gonadotropins. Chian et al5 reported that rates of oocyte maturation and pregnancy could be improved by hCG priming 36 h before immature oocytes retrieval in women with PCOS.
