Clinical Studies of FET

Some clinical studies have shown that hormonal interventions can be harmful to endometrial receptivity and pregnancy success. Thus, in the absence of hormonal intervention, the true effect size of the FET in the natural cycle may be higher. Importantly, more than 1,000 patients have been recruited to new multicenter randomized trials (Antarctic trials) to assess the impact of natural and artificial FET cycles on numerous outcomes such as living, health costs, adverse events, and suffering and their outcomes are eagerly anticipated.

Studies validating these positive outcomes for women who are older or poor responders and natural cycle FET are certainly necessary, but the evidence so far further solidifies the principle that better and safer pregnancy outcomes can be achieved with FET, and therefore, the burden of proof now seems to have shifted to those advocating fresh embryo transfer.