Day 4 versus day 3 embryo transfer: a prospective study of clinical outcomes

ObjectiveTo compare the clinical outcomes after day 4 or day 3 embryo transfers in controlled ovarian hyperstimulation-IVF/intracytoplasmic sperm injection (ICSI) cycles.DesignProspective randomized study.SettingCenter for Human Reproduction, ‘Genesis Athens’ Clinic (private gynecological and surgical clinic), Athens, Greece.Patient(s)Three hundred fifty women with primary infertility and indication for IVF/ICSI treatment. Patients were randomly allocated to day 4 or day 3 embryo transfer.Intervention(s)Controlled ovarian hyperstimulation, oocyte retrieval, IVF/ICSI, embryo transfer.Main Outcome Measure(s)Implantation rate; clinical, ongoing, and multiple pregnancy rates.Result(s)A trend toward higher clinical and ongoing pregnancy rates was noted after day 4 embryo transfers. Implantation and multiple pregnancy rates were comparable after day 4 or day 3 embryo transfers.Conclusion(s)The transfer of day 4 embryos in IVF/ICSI cycles may result in favorable implantation and pregnancy rates which are at least comparable to those after the transfer of day 3 embryos.