The Debate on Single Embryo Transfer in IVF/ICSI —What Should the Indications for eSET Be

The incidence of multiple pregnancies after in-vitro fertilisation or intracytoplasmic sperm injection (IVF/ICSI) is much higher than after natural conception. It is well known that multiple pregnancies have a less favorable obstetric, neonatal outcome than singletons. It is obvious that a strategy using transfer of only one embryo would result in singletons, but it might also result in a considerable decline in the overall birth rate. Data from randomized controlled trials (RCTs) indicate that single-embryo transfer (SET) results in lower live birth rates per fresh IVF cycle than double-embryo transfer (DET). However, the expectation is that cumulative live birth rates are comparable in the two groups. Twin pregnancies in IVF should be avoided by transferring embryos one at a time, even for frozen cycles. SET is unlikely to be suitable for all women undergoing IVF and outcomes may be sensitive to different laboratory protocols. Other factors affecting the routine use of SET include laboratory techniques, individual preferences and funding issues. An important issue is how to select patients suitable for SET and embryos with a high implantation potential. In the present study, we review data at our clinic in addition to the literature regarding elective single-embryo transfer (eSET) in IVF/ICSI.