Biphasic in-vitro maturation: an advancement over traditional in-vitro maturation

Culture conditions for standard in-vitro maturation (IVM) have remained largely unchanged for more than 50 years and are non-physiological, limiting the success of this form of assisted reproductive technology (ART). Advances in the understanding of oocyte biology have led to the development of biphasic oocyte maturation approaches, such as IVM with a pre-maturation step, exemplified by capacitation IVM (CAPA-IVM). Biphasic IVM protocols consist of two steps: a pre-IVM step (to enhance germinal vesicle oocyte development) and an IVM step. The key role of the pre-IVM step in CAPA-IVM is the use of C-type natriuretic peptide and estradiol in the pre-IVM culture medium to maintain oocyte meiotic arrest. Oocytes are then cultured in conventional IVM media to complete nuclear maturation. The main current indications for biphasic IVM are polycystic ovary syndrome and high antral follicle count. There have been eight trials of biphasic IVM, with a total of 483 cycles and 189 live births. IVFMD, My Duc Hospital, Ho Chi Minh City, Vietnam is the only centre to have reported live birth outcomes after the use of biphasic IVM. No cases of ovarian hyperstimulation syndrome have been reported with biphasic IVM. In one study comparing biphasic IVM with conventional in-vitro fertilization (IVF), there were no significant differences between the CAPA-IVM and IVF groups with respect to the occurrence of pregnancy complications, obstetric and perinatal complications, preterm delivery, birth weight and neonatal complications. Preliminary data also support normal developmental outcomes up to 24 months for children born after biphasic IVM. Biphasic IVM represents a promising advancement in ART.