A stronger argument to support the adoption of FET as a default IVF protocol is the potential for higher pregnancy rates. A systematic review and meta-analysis of three randomized controlled trials, including 633 women, assessed clinical and ongoing CPRS and abortion rates after effect and fresh embryo transfer. The overall conclusion is that FET leads to an increase in cardiopulmonary resuscitation and a persistent pregnancy rate with no difference in abortion rates.
It is important to interpret these data with vigilance. It remains to be seen whether these findings apply to women with poorer prognostic outcomes. However, a preliminary study was conducted for women over 35 years of age, and it appears that these findings may prove to be in “poor prognosticate” populations.
In addition, it did not report the live-birth rate, although a meta-analysis found that conclusions based on the clinical efficacy of pregnancy or live births as a terminal. It will certainly be more reassuring to find that the cumulative living rate retrieved from one oocyte is equal. Finally, in the absence of health economic data, the cost implications of these two strategies (fresh or frozen transfers) remain unclear.