Maternal and perinatal outcomes after fresh versus frozen embryo transfer-what is the risk-benefit ratio?

Fresh ET has been the conventional strategy in IVF, but there is a growing opinion suggesting that its maternal and perinatal outcomes can be enhanced by a policy of elective freezing of embryos, followed by transfer at a later date. Available studies suggest a number of improved maternal and perinatal outcomes after frozen ET, although there is also a suggestion of large for gestational age babies associated with this strategy. The observational nature of the available data limit our confidence in the results of available studies. A genuinely unbiased estimate of the advantages of a policy of elective ET can only be confirmed by a definitive randomized controlled trial with an adequate length of follow-up of the offspring.