Can fresh embryo transfers be replaced by cryopreserved-thawed embryo transfers in assisted reproductive cycles? A randomized controlled trial

PurposeControlled ovarian hyperstimulation has been shown to advance endometrial maturation and adversely affects implantation in ART. It has been reported that there is a better embryo-endometrium synchrony in frozen-thawed embryo transfer cycles than fresh embryo transfer cycles. The objective of this study was to compare ongoing pregnancy rates between fresh ET and FET cycles.MethodsIn an open prospective, controlled study, the patients who were classified as high responders, were randomized to either fresh ET or FET. The embryos in FET group were cryopreserved with vitrification by Cryotop method.ResultsA total of 374 patients were included, 187 of which were randomized to FET and 187 to fresh ET. There were 39% (n = 73) ongoing pregnancy in FET group compared with 27.8% (n = 52) in fresh ET group[odds ratio = 1.66;95% confidence interval = 1.07-2.56; p = 0.02].ConclusionsFETs can be performed instead of fresh ETs to improve the outcome of ART in highly selected patients.