Combination of IVF and IVM in naturally cycling women

This study investigated the combination of an unstimulated IVF cycle with in-vitro maturation (IVM) of additional immature cumulus–oocyte–complexes (COC) from the same cycle collected at the same time as the spontaneous preovulatory follicle. This could potentially improve rates of embryo transfer and pregnancy/live births compared with conventional unstimulated IVF treatment and at the same time eliminate the risk of ovarian hyperstimulation syndrome. This prospective trial included 77 women with regular menstrual cycles. Age at inclusion was between 20 and 37 years. Results showed a retrieval rate of mature oocytes of 50/80 (62.5%) per cycle started and immature COC were collected in 74/80 (92.5%) cycles. The embryo transfer rate was 28/80 (35.0%) with mature oocytes and increased in total to 43/80 (53.8%) with IVM oocytes. Corresponding birth rates per transfer were 3/28 (10.7%) and 4/43 (9.3%). Birth rates per aspiration were 3/76 (3.9%) and 4/76 (5.3%). It is concluded that the protocol described here shows proof of concept, but the impact of the IVM procedure only reached a significant level regarding embryo transfer, not with live births. The reason for this is yet unclear, but asynchrony between endometrial factors and IVM oocytes together with unknown competence of IVM embryos is suspected.