Dose of recombinant FSH and oestradiol concentration on day of HCG affect embryo development kinetics

Abstract

During follicular growth, the follicle is exposed to an almost ever-changing composition of isoforms of FSH and LH, which causes a number of different and divergent biological effects. Through a time-lapse system, embryo kinetics were examined following the use of FSH only (recombinant FSH, rFSH) and gonadotrophins containing LH activity (human menopausal gonadotrophin, HMG, and FSH+HMG) in oocyte donors. No significant differences were seen between the three groups (for rFSH, HMG and rFSH+HMG, t2 was 27.8h, 27.9h and 27.5h respectively). Moreover, although embryos obtained with rFSH showed an increase in the proportions of optimal timings of development, the differences observed were not significant, as shown by the percentages of embryos inside/outside these kinetic variables. In contrast, for gonadotrophin dosage and oestradiol concentration, this study observed differences in embryo development kinetics for some of the variables evaluated, which allowed the description of an optimal range of gonadotrophin dosage and oestradiol concentration. However, these kinetic differences did not translate into important distinctions in the proportion of optimal embryos with a higher implantation potential.The use of assisted reproduction treatment has been increasing since the birth of the first test-tube baby in 1978 and, in developed countries, it accounts for a relatively high percentage of annual births. In an attempt to compensate for inefficiencies in IVF procedures, patients undergo ovarian stimulation, using high doses of exogenous gonadotrophins to allow retrieval of multiple oocytes in a single cycle. Although ovarian stimulation has an important role in assisted reproduction, it may also have detrimental effects on oogenesis, embryo quality, endometrial receptivity and perinatal outcomes. We report the use of an incubator with video time-lapse recording and image analysis that can determine precisely the timing of key events during embryo development which may act as markers of quality and viability. Through this novel technology, we aimed to establish if there are any links between different parameters of the ovarian stimulation and embryo development kinetics and hence embryo quality and implantation potential.