Objective: To determine the possibility of obtaining good pregnancy rates (PRs) after freezing and thawing cocultured blastocysts.
Design: Human blastocysts were frozen first according to a protocol available from literature. Two other protocols including the addition of glycerol were designed to improve the results.
Setting: All the patients were under clinical management at the Institut Rhonalpin pour l'Etude de la Reproduction Humaine in Lyons, France.
Patients: Patients involved in the in vitro fertilization program have had their supernumerary embryos frozen according to the three protocols presented here.
Main outcome measures: Embryo recovery after freezing and thawing. Clinical and ongoing pregnancies after embryo transfer (ET).
Results: A protocol including sucrose addition and reduction of steps in the preparation of the blastocysts for freezing gave us a 21% PR per transfer (15 ongoing) of 101 transfers (106 thawings).
Conclusions: Freezing of cocultured human blastocysts allow good PRs. This can represent an alternative for repeated failures of ETs at early stages.