The initiation of in vitro fertilization (IVF) treatment involves preparing the woman. This preparation is carried out using two primary protocols: The long (agonist) protocol typically begins on day 21 of the menstrual cycle, with egg retrieval occurring approximately 3-3.5 weeks later. The short (antagonist) protocol, on the other hand, starts directly on day 2-3 of the menstrual cycle, and egg retrieval is completed within approximately 10-12 days. Following egg retrieval, the transfer of the resulting embryos into the uterus is determined based on the patient's individual conditions and the physician's clinical assessment. This transfer can be performed as a fresh embryo transfer (during the same period as egg retrieval) or as a frozen-thawed embryo transfer (where embryos are frozen, stored, and then transferred at a later, more suitable time determined by the physician).