In vitro Human Embryo Culture; When Questions Outweigh Answers

More than five million babies have been born by the application of assisted conception methods throughout the world, and about 1% to 2% of babies in developed countries are born by the help of assisted reproductive techniques (ART) in couples with infertility. In spite of huge developments in equipments, techniques, procedures , supplies and greater control of environmental factors which affect assisted conception processes, there is mounting concern regarding anomalies and birth defects from assisted conception in the community and, especially, among infertile couples. Although this concern is very low compared to the time of application of IVF technology three decades ago, but results of more comprehensive longitudinal studies have revealed increased risk of congenital anomalies, malformation and early pregnancy loss associated with ART(1). What really increases the defects, or whether these defects are transferred through parental gametes to the offspring or whether suboptimal in vitro conditions cause permanent changes in gametes or embryos that will influence the future life of IVF babies are not clearly known yet. Comparison of babies conceived through ART with babies of infertile/subfertile couples conceived without these techniques and those of fertile couples emphasize the role of optimization of assisted conception processes on their success rate and on the present and future health of these babies. Several important factors influencing the quality and health of gametes and embryos in ART are the candidates themselves and the conditions, suboptimal for instance, under which ART processes are run. The factors also include conditions influencing controlled ovarian stimulation, gametes retrieval and processing, fertilization techniques and in vitro embryo cultures. Duration and condition of in vitro embryo culture have critical roles in IVF success rate and susceptibility of babies to different diseases in future. A large number of variables can affect development and quality of embryos during in vitro culture, including culture media, quantity of embryos, volume of each droplet, temperature, gas phase composition and quality, IVF laboratory air quality, culture ware/contact supplies, overlay oil, number and capacity of incubators, equipment validation and many other factors that need precise control during in vitro embryonic development (2). Regarding the large number of variables influencing in vitro culture of embryos, a question is raised whether which of the aforesaid factors could be of more importance and need greater attention and whether we really could control all these variables precisely similar to the controlling systems in the fallopian tubes and the uterus. …