The likelihood of live birth and multiple birth after single versus double embryo transfer at the cleavage stage: a systematic review and meta-analysis

Objective To determine whether a policy of elective single-embryo transfer (e-SET) lowers the multiple birth rate without compromising the live birth rate. Design Systematic review and meta-analysis. Setting Tertiary referral center for reproductive medicine and IVF unit. Patient(s) None. Intervention(s) Searches of the Cochrane Controlled Trials Register, Meta-register for Randomized Controlled Trials (RCTs), EMBASE, MEDLINE, and SCISEARCH with no limitation on language and publication year, 1974 to 2008. Selection criteria: randomized, controlled trials comparing e-SET with double-embryo transfer (DET) for live birth and multiple birth rates after in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI). Nonrandomized trials and studies that included only patients who had blastocyst transfer were excluded. Main Outcome Measure(s) The likelihood of live birth per patient and multiple birth per total number of live births. Other outcomes included implantation rate, pregnancy rate, miscarriage and ectopic pregnancy rates, clinical pregnancy rate, ongoing pregnancy rate per patient, and preterm delivery rate per live birth. Result(s) Six trials (n = 1354 patients) were included in the meta-analysis. Compared with DET, the e-SET policy was associated with a statistically significant reduction in the probability of live birth (RR 0.62; 95% CI, 0.53–0.72) and multiple birth (RR 0.06; 95% CI, 0.02–0.18). Conclusion(s) Elective-SET of embryos at the cleavage stage reduces the likelihood of live birth by 38% and multiple birth by 94%. Evidence from randomized, controlled trials suggests that increasing the number of e-SET attempts (fresh and/or frozen) results in a cumulative live birth rate similar to that of DET. Offering subfertile women three cycles of IVF will have a major impact on the uptake of an e-SET policy.