In vitro fertilization (IVF) accounts for >4% of live births in Israel. Identifying the oocytes that have the capacity to be fertilized, to undergo preimplantation embryo development and to implant within the uterus can significantly reduce clinical complications and shorten time to pregnancy. A large fraction of the oocytes is fertilized in the clinic via intracytoplasmic sperm injection (ICSI). We developed a method for evaluating the viscoelastic properties of the cytoplasmic mass of the oocytes based on ICSI procedure. Applying our algorithm on human oocytes shows a statistically significant correlation with fertilization rate, preimplantation embryo development and implantation rate. Testing our method on murine oocytes reveals that the actin and microtubule cytoskeleton networks and myosin contractility are responsible for the mechanical properties that are observed in human oocytes. To test the involvement of the energetic reserves of the oocytes, we apply enzymatic assays to measure ATP content in real time. This work has the potential to improve current IVF procedures in human clinics and in domestic animals.