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Type: Journal article
Title: Clinical effectiveness of elective single versus double embryo transfer: meta-analysis of individual patient data from randomised trials
Author: McLemon, D.
Harrild, K.
Bergh, C.
Davies, M.
de Neubourg, D.
Demoulin, J.
Gerris, J.
Kremer, J.
Martikainen, H.
Mol, B.
Norman, R.
Thurin-Kjellberg, A.
Tiitinen, A.
van Montfoort, A.
van Peperstraten, A.
van Royen, E.
Bhattacharya, S.
Citation: British Medical Journal, 2010; 341(7787):C6945:1-C6945:13
Publisher: British Med Journal Publ Group
Issue Date: 2010
ISSN: 0959-535X
Statement of
D J McLernon, K Harrild, C Bergh, M J Davies, D de Neubourg, J C M Dumoulin, J Gerris, J A M Kremer, H Martikainen, B W Mol, R J Norman, A Thurin-Kjellberg, A Tiitinen, A P A van Montfoort, A M van Peperstraten, E Van Royen, S Bhattacharya
Abstract: Objective: To compare the effectiveness of elective single embryo transfer versus double embryo transfer on the outcomes of live birth, multiple live birth, miscarriage, preterm birth, term singleton birth, and low birth weight after fresh embryo transfer, and on the outcomes of cumulative live birth and multiple live birth after fresh and frozen embryo transfers. Design: One stage meta-analysis of individual patient data. Data sources: A systematic review of English and non-English articles from Medline, Embase, and the Cochrane Central Register of Controlled Trials (up to 2008). Additional studies were identified by contact with clinical experts and searches of bibliographies of all relevant primary articles. Search terms included embryo transfer, randomised controlled trial, controlled clinical trial, single embryo transfer, and double embryo transfer. Review methods: Comparisons of the clinical effectiveness of cleavage stage (day 2 or 3) elective single versus double embryo transfer after fresh or frozen in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatments were included. Trials were included if the intervention differed only in terms of the intended number of embryos to be transferred. Trials that involved only blastocyst (day five) transfers were excluded. Results: Individual patient data were received for every patient recruited to all eight eligible trials (n=1367). A total of 683 and 684 women randomised to the single and double embryo transfer arms, respectively, were included in the analysis. Baseline characteristics in the two groups were comparable. The overall live birth rate in a fresh IVF cycle was lower after single (181/683, 27%) than double embryo transfer (285/683, 42%) (adjusted odds ratio 0.50, 95% confidence interval 0.39 to 0.63), as was the multiple birth rate (3/181 (2%) v 84/285 (29%)) (0.04, 0.01 to 0.12). An additional frozen single embryo transfer, however, resulted in a cumulative live birth rate not significantly lower than the rate after one fresh double embryo transfer (132/350 (38%) v 149/353 (42%) (0.85, 0.62 to 1.15), with a minimal cumulative risk of multiple birth (1/132 (1%) v 47/149 (32%)). The odds of a term singleton birth (that is, over 37 weeks) after elective single embryo transfer was almost five times higher than the odds after double embryo transfer (4.93, 2.98 to 8.18). Conclusions: Elective single embryo transfer results in a higher chance of delivering a term singleton live birth compared with double embryo transfer. Although this strategy yields a lower pregnancy rate than a double embryo transfer in a fresh IVF cycle, this difference is almost completely overcome by an additional frozen single embryo transfer cycle. The multiple pregnancy rate after elective single embryo transfer is comparable with that observed in spontaneous pregnancies.
Keywords: Humans; Abortion, Spontaneous; Embryo Transfer; Fertilization in Vitro; Pregnancy Rate; Maternal Age; Pregnancy; Pregnancy, Multiple; Adult; Female; Live Birth; Randomized Controlled Trials as Topic
Description: Extent: 13p.
Rights: This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: and
RMID: 0020101799
DOI: 10.1136/bmj.c6945
Appears in Collections:Obstetrics and Gynaecology publications

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