The Fischer protocol for assisted reproductive technology treatment: Real-world data experience comparing elective single versus double embryo transfer with or without comprehensive chromosome screening

High rates of multiple implantation after assisted reproductive technology (ART) treatment represent one of the major problems for both mothers and their fetuses. Given the availability of techniques intended to identify embryos with the highest chance for development to term, such as comprehensive chromosome screening (CCS) and blastocyst transfer, the decision on the number of embryos to transfer deserves careful consideration. This report presents real-life data from two clinics using the Fischer protocol for cycle programming in patients undergoing ART. Our data indicate that ovarian stimulation using the Fischer protocol provides consistent and optimal ART outcomes in centers following strict quality management standards. However, high multiple implantation rates were observed in fresh and frozen transfer cycles after transferring two embryos - even in patients aged over 39 years. The live birth rates after CCS were superior to those using untested embryos. These findings were held for the three age groups irrespective of the CCS culture day (D1 = PN stages, or D5 = blastocysts). Our results support a single embryo transfer policy, particularly in women under 34 years of age with favorable conditions during ART treatment, i.e., a high number of available fertilized oocytes.