The first step in in-vitro fertilization (IVF) is preparing the woman. This preparation can be done in two ways: a long protocol, starting on day 21 of the menstrual cycle and taking approximately 3-3.5 weeks to reach egg retrieval; or a short (antagonist) protocol, starting on days 2-3 of the menstrual cycle and taking approximately 10-12 days to reach egg retrieval. Embryo transfer is then performed either fresh (at the same time as egg retrieval) or frozen-thawed (embryos are frozen and stored, then transferred at a later date determined by the physician), depending on the patient's individual circumstances and the physician's preferences.