IVF means taking one or more eggs from the ovary and fertilizing them outside the body, then returning the fertilized eggs (embryos) to the uterus via the cervix. IVF has passed through several stages, starting with the classical test tube baby over 35 years ago and moving up to Intracytoplasmic Sperm Injection (ICSI) where an individual sperm is injected into an embryo using microscopic techniques.