Comparisons of benefits and risks of single embryo transfer versus double embryo transfer: a systematic review and meta-analysis

Abstract

Background Evidence referring to the trade-offs between the benefits and risks of single embryo transfer (SET) versus double embryo transfer (DET) following assisted reproduction technology are insufficient, especially for those women with a defined embryo quality or advanced age. Methods A systematic review and meta-analysis was conducted according to PRISMA guidelines. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched based on established search strategy from inception through February 2021. Pre-specified primary outcomes were live birth rate (LBR) and multiple pregnancy rate (MPR). Odds ratio (OR) with 95% confidence interval (CI) were pooled by a random-effects model using R version 4.1.0. Results Eighty-five studies (14 randomized controlled trials and 71 observational studies) were eligible. Compared with DET, SET decreased the probability of a live birth (OR = 0.78, 95% CI: 0.71–0.85, P < 0.001, n = 62), and lowered the rate of multiple pregnancy (0.05, 0.04–0.06, P < 0.001, n = 45). In the sub-analyses of age stratification, both the differences of LBR (0.87, 0.54–1.40, P = 0.565, n = 4) and MPR (0.34, 0.06–2.03, P = 0.236, n = 3) between SET and DET groups became insignificant in patients aged ≥40 years. No significant difference in LBR for single GQE versus two embryos of mixed quality [GQE + PQE (non-good quality embryo)] (0.99, 0.77–1.27, P = 0.915, n = 8), nor any difference of MPR in single PQE versus two PQEs (0.23, 0.04–1.49, P = 0.123, n = 6). Moreover, women who conceived through SET were associated with lower risks of poor outcomes, including cesarean section (0.64, 0.43-0.94), antepartum haemorrhage (0.35, 0.15-0.82), preterm birth (0.25, 0.21-0.30), low birth weight (0.20, 0.16-0.25), Apgar1 < 7 rate (0.12, 0.02-0.93) or neonatal intensive care unit admission (0.30, 0.14-0.66) than those following DET. Conclusions In women aged < 40 years or if any GQE is available, SET should be incorporated into clinical practice. While in the absence of GQEs, DET may be preferable. However, for elderly women aged ≥40 years, current evidence is not enough to recommend an appropriate number of embryo transfer. The findings need to be further confirmed.

Comparison of frozen-thawed embryo transfer strategies for the treatment of infertility in young women: a retrospective study

“…According to a recent meta-analysis ( Ma et al., 2022 ), for young patients, SET has a lower live birth rate and a lower rate of gemellary pregnancy than DET. Considering the risks of gemellary pregnancy, we believe that SET may be more beneficial.…”

The Application of Artificial Intelligence in Predicting Embryo Transfer Outcome of Recurrent Implantation Failure

“…Due to the lack of clear evidence-based medical guidelines for the number of embryos to be transferred in RIF patients, how to obtain the highest single cycle pregnancy success rate with as few embryos transferred as possible while avoiding multiple pregnancy as much as possible, that is, how to balance the pregnancy success rate and multiple pregnancy rate, is a great challenge for clinicians and RIF patients ( Tobias et al, 2016 ; Kamath et al, 2020 ; Ma et al, 2022 ). We urgently need an effective and reliable assisted decision-making method to help clinicians find this balance, and the computer-aided decision-making system will provide an efficient solution.…”

Risk factors for twin pregnancy in women undergoing double cleavage embryo transfer

“…More recently, elective single embryo transfer has been increasingly popular. However, the decision towards elective single embryo transfer or double embryo transfer remains inconclusive up to now [ 30 , 31 ], which needs to be further explored.…”