Sequential embryo transfer (SET) is an improved method of increasing pregnancy rates and implantation rates in infertile couples. According to the  American Society for Reproductive Medicine (ASRM), the average pregnancy rate is about 20% for patients undergoing in vitro fertilization (IVF) treatment. Patients undergoing SET have a pregnancy rate of over 50%! SET is the transfer of two groups of embryos in the same menstrual cycle of a woman undergoing IVF treatment for infertility. One group of embryos-the best looking and fastest growing embryos are transferred to the uterus 2 or 3 days after the oocytes (human eggs) are collected from the ovary. The second, more highly developed, group of embryos are transferred to the uterus a few days later when at least one embryo has reached the expanded blastocyst stage-an advanced stage when an embryo is about to hatch from its shell called the Zona Pellucida and attempts to implant in the lining of the uterus called the endometrium. SET has an increased implantation rate (embryos implanting from the total number of embryos).