Meta-analysis Reports Lower Clinical Pregnancy Rates and Live Births with Single Embryo Transfer in Fresh IVF/ICSI Cycles

A recent meta-analysis has reported that elective single embryo transfer (eSET), compared to double embryo transfer (DET), lowers ongoing pregnancy and live birth rates in fresh IVF/ICSI cycles. The study results have been published in the recent issue of the journal, Reproductive Biology and Endocrinology.

Ricardo LR Baruffi from the Center for Human Reproduction, Sao Paolo, Brazil, and coworkers, conducted the meta-analysis of trials selected from various databases (1995 to 2008) to compare the IVF/ICSI treatment outcomes between SET and DET. The odds ratio (OR) was calculated with a fixed-effect model, and the Mantel Haenszel method was used to determine the fixed-effect effectiveness. The study results are listed in the table below.

Parameters DET SET Odds Ratio
Implantation rate 34.5% 34.7% 0.99
Ongoing clinical pregnancy rate 44.5% 28.3% 2.06
Live birth rate 42.5% 28.4% 1.87

The findings demonstrated that DET was associated with nearly 1.64 to 2.60 times better chances of ongoing clinical pregnancy rate, and 1.44 to 2.42 times higher live birth rate as opposed to SET. However, the scientists did not find any statistically significant difference with respect to the implantation rates between the two groups.

To assess and compare the effectiveness of SET and DET, earlier Pandian et al (Human Reproduction, 2005) had conducted a systematic review of randomized controlled trials obtained from databases such as Medline, Cochrane, and EMBASE, using the cochrane collaboration review method. The researchers observed a greater birth rate per woman in fresh IVF treatment cycle with DET compared to SET (OR=1.94). However, clearly, DET was also associated with a substantially increased multiple pregnancy rate (OR=62.83). Based on the findings, it was concluded that although SET significantly decreases the risk of multiple gestation, it also reduces the probability of live births in fresh IVF cycles. Live birth rate similar to that of DET could be attained with the transfer of a single fresh embryo when it is followed by a frozen-thawed embryo transfer (OR=1.19).

Lower effectiveness and the higher costs associated with eSET and cryopreservation have always remained a big concern, particularly in developing countries, despite its efficacy in reducing ART-associated multiple birth rates.

Interestingly, a more recent meta-analysis by Gelbaya et al (Fertility and Sterility, 2009) also suggested that the likelihood of live births and multiple births were lowered by 38% and 94%, respectively, with the transfer of single cleavage-stage embryos. The investigators further proposed that a cumulative live birth rate comparable to that of DET could be achieved by increasing the number of attempts of elective single embryo (fresh and/or frozen) transfer. Several other studies have also demonstrated that eSET with cryopreservation is cost effective and improves the treatment outcomes in IVF/ICSI cycles.

Another recent study by Veleva et al (Human Reproduction, 2009) substantiated the cost-effectiveness and efficacy of eSET in combination with a cryopreservation program. The researchers compared clinical outcomes of ART during 1995 to 1999, when DET was more prevalent, and 2000 to 2004, during which time eSET was widely adopted. The primary clinical outcome measure was cumulative term live birth rate per woman. Considering the hospital charges and the cost of drugs used for the treatment, the incremental cost-effectiveness ratio of term live birth was also assessed.

The results showed that the cumulative pregnancy and cumulative live birth rates per oocyte pickup, as well as cumulative live birth rate per woman, were significantly greater during the eSET period in contrast to DET period. Also, the estimated expense of a term live birth during the eSET period were found to be 19,889 euros (approximately $27,844) less than that in the DET period.

The Practice Committee of the American Society for Reproductive Medicine (ASRM) and the Society for Assisted Reproductive Technology (SART) revised its guidelines on embryo transfer in 2008 to decrease the incidence of higher order multiple pregnancies and improve IVF success rates. The committee recommends single embryo transfer for women below 35 years with a favorable prognosis, while not more than 2 embryos (cleavage stage and blastocyst) transfers for all others in the same age group. The guidelines further suggest that the number of cleavage-stage embryos transferred for all patients having a more favorable prognosis, should not be more than 2, 3, and 5 for those aged 35 to 37 years, 38 to 40 years, and >40 years, respectively.

The Human Fertilisation and Embryo Authority (HFEA), a statutory body regulating all fertility clinics in the UK, also recommends that elective single embryo programs must be accompanied with effective cryopreservation protocols for maximizing the cumulative live birth rates.


1. Baruffi RL, Mauri AL, Petersen CG, et al. Single-embryo transfer reduces clinical pregnancy rates and live births in fresh IVF and Intracytoplasmic Sperm Injection (ICSI) cycles: a meta-analysis. Reprod Biol Endocrinol. 2009 Apr 23;7:36.

2. Pandian Z, Templeton A, Serour G, Bhattacharya S. Number of embryos for transfer after IVF and ICSI: a Cochrane review. Hum Reprod. 2005 Oct;20(10):2681-7.

3. Gelbaya TA, Tsoumpou I, Nardo LG. The likelihood of live birth and multiple birth after single versus double embryo transfer at the cleavage stage: a systematic review and meta-analysis. Fertil Steril. 2009 May 14. [Epub ahead of print].

4. Veleva Z, Karinen P, Tomás C, Tapanainen JS, Martikainen H. Elective single embryo transfer with cryopreservation improves the outcome and diminishes the costs of IVF/ICSI. Hum Reprod. 2009 Mar 24. [Epub ahead of print]

5. Practice Committee of Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Guidelines on number of embryos transferred. Fertil Steril. 2008 Nov;90(5 Suppl):S163-4.

6. Min JK, Claman P, Hughes E; Society of Obstetricians and Gynecologists of Canada; Canadian Fertility and Andrology Society. Guidelines for the number of embryos to transfer following in vitro fertilization. J Obstet Gynaecol Can. 2006 Sep;28(9):799-813.

One Response to “Meta-analysis Reports Lower Clinical Pregnancy Rates and Live Births with Single Embryo Transfer in Fresh IVF/ICSI Cycles”

  1. kerryfa says:

    It is a positive development that research and the media has shed light on the incidence on multiples. However, it is important to remember that most doctors try and make the best decisions for their patients. Often, only multiple embryos will be transferred if the quality of those blastocysts is poor. While it is good to have some guidelines to avoid situations like the “octomom”, doctors are still the most qualified to make these decisions. I encourage you to visit to learn more about fertility issues and see how people are dealing with these situations. Don’t miss our latest blog on Jon & Kate Gosselin of Jon and Kate plus 8.


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