The decision on the number of embryos to transfer after an IVF cycle is based on the number of available embryos, the quality of the embryos, the patient's age, and the goal of limiting multiple gestations. Stanford Fertility Center and most IVF centers examine the embryos on the third day after oocyte (egg) retrieval to select for the best quality embryos to transfer, and depending on quality, the remaining embryos are frozen to be used in the future. Patients with a limited number of embryos, those that plan to replace all available embryos after an IVF cycle, do not need to wait until the third day after oocyte retrieval to select embryos, and may replace the embryos on the second day after the oocyte retrieval. We are examining whether pregnancy rates differ among these patients based on the day of embryo transfer (Day 2 vs. Day3). Patients must be undergoing IVF treatment at Stanford University and patients will not receive compensation for their participation (no medical costs covered or patient payment for participation).
