Fresh versus frozen: initial transfer or cumulative cycle results: how do we interpret results and design studies?

This review approaches the question of selecting the most appropriate embryo transfer strategy through use of classic study design for a randomized trial.

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Volume 106, Issue 2, Pages 251-256


Marcelle I. Cedars, M.D.


The way we practice assisted reproductive technology has changed over time. In many ways these changes have been positive as technology has improved, in vitro culture has improved, and embryo selection increasingly allows a single embryo transfer with high success rates and ever smaller multiple birth rates. However, our specialty has often been criticized for not being critical with respect to the acceptance of new technology. Although the outcome of interest seems clear (increasing birth of a healthy baby), the approach can be more complicated; and as there is a de-linking of egg retrieval and ET, and as costs and procedures increase, we should be rigorous about our acceptance of change. This is not to stall change but to encourage the same rigor and questioning of accepted dogma expected in other fields of medicine. An approach based on standard clinical study design to allow appropriate comparisons between patients, and to allow the most comprehensive information for patient counseling, is presented.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility┬« is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.