Hyaluronan-enriched transfer medium in cleavage-stage frozen-thawed embryo transfers increases implantation rate without improvement of delivery rate

ObjectiveTo investigate the efficacy of hyaluronan-enriched transfer media in cleavage-stage frozen embryo transfer cycles.DesignTwo commercially available transfer media were prospectively compared in an observational study.SettingHospital-based in vitro fertilization clinic.Patient(s)Patients (n = 425) undergoing frozen-thawed embryo transfer (FET). The embryos transferred were included in either a study group (high hyaluronic acid [HA], n = 199) or a control group (low HA, n = 226).Intervention(s)Delivery rate per FET; positive hCG rate, biochemical pregnancy rate, clinical pregnancy rate, implantation rate, and clinical abortion rate were secondary outcomes.Result(s)The use of HA in the transfer media significantly increased the positive hCG rate (37.2% vs. 25.2%) and implantation rate (23.1% vs. 15.8%) without increasing the delivery rate (21.6% vs. 21.2%). More subjects in the study group with a positive hCG test experienced biochemical pregnancy (28.4% vs. 8.9%).Conclusion(s)Addition of HA to transfer media seems to favor attachment of early embryos in FETs without increasing the delivery rate.