Meta‐analysis of the embryo freezing transfer interval

Abstract

Background The decision of whether frozen embryo transfer (FET) should be performed in the cycle immediately after OPU or at least one cycle later is controversial. FET could improve pregnancy rates in IVF; however, how much time is needed for the endometrium to return to optimal receptivity after ovarian stimulation is not known. Methods Electronic search in MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials to identify studies providing data on the influence of the interval between embryo freezing (or OPU) and FET in FET cycles published between January 1, 2007, and February 1, 2020. Main findings Data analyzed indicated that in the immediate FET cycles, there was a trend to an increased biochemical pregnancy rate (RR = 1.08; CI = 1.00‐1.18), whereas the clinical pregnancy rate was somewhat higher, but without reaching statistical significance (RR = 1.07; CI = 0.99‐1.15). The live birth rate was similar in the two groups (RR = 1.05; CI = 0.95‐1.15), as was the implantation rate (RR = 0.98; CI = 0.83‐1.16). Stratifying by embryo stage or FET type (freeze‐all or FET after failed fresh transfer) showed no differences. Conclusion Systematically delaying FET does not offer benefits to IVF outcomes. In addition, immediate transfer is associated with a nonsignificant trend to better clinical pregnancy rate and it also avoids the psychological effects of prolonging the stress on prospective parents.

It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

“…In our study, an immediate FET did not improve nor worsen the clinical outcome, but it shortened the time patients wait to be pregnant successfully, which alleviated their anxiety compared with those in the postponed FET group. Our results were consistent with two recently published meta-analysis that did not find any association between the timing of FET and pregnancy outcomes ( 11 , 32 ).…”

microRNA-based signatures obtained from endometrial fluid identify implantative endometrium

“…The samples were collected during the natural cycle, 16–21 days after the beginning of menstruation. To test the selected method, the samples were collected just before Day-5 frozen ETs, a practice which is performed increasingly often ( Matorras et al , 2021 ). Out of 162 women ( Supplementary Fig.…”

Aspiration of excess follicles before intrauterine insemination in high response cycles

“…One of the major challenges in current assisted reproductive techniques (ART) is preventing multiple pregnancies 5–8 9 one of the most important favorable prognostic factors, can be completely isolated from multiple pregnancy risk as a result of single embryo transfer policies and frozen embryo programs 10 . In contrast, in IUI, ovarian response is directly related to both PR overall 11 and multiple PR, including high‐order multiple pregnancies 11–13 …”

“…[5][6][7][8] Nowadays, this can be achieved relatively easily in IVF, since ovarian response, 9 one of the most important favorable prognostic factors, can be completely isolated from multiple pregnancy risk as a result of single embryo transfer policies and frozen embryo programs. 10 In contrast, in IUI, ovarian response is directly related to both PR overall 11 and multiple PR, including high-order multiple pregnancies. [11][12][13] In a meta-analysis, the PR in IUI cycles with monofollicular growth was 8.4% compared with 13.4%, 16.4%, and 16.4% in cycles with two, three, and four follicles.…”