Abstract
Twin pregnancies are widely considered to carry higher risks for mothers and offspring than singleton deliveries. Therefore, authorities have increasingly argued in favor of reducing the high prevalence of twin pregnancies after fertility treatments. Attempts at such a reduction with IVF have been the primary motivation for the increasing popularity of single-embryo transfer (SET). If it were to be proved that the outcome risks of twin pregnancies do not exceed those of singletons and if data suggested that twin pregnancies may, indeed, represent a more cost-effective approach for most infertility patients towards building a family, the basic rationale for SET would, therefore, be eliminated. Such data were recently developed and are reviewed here. The conclusions from those data are that, in a vast majority of infertility patients, SET is outright contraindicated and should not be offered, except as part of experimental studies and with appropriate informed consents. Only patients with obstetrical contraindications to twinning and infertility patients with specific desire for only one offspring should be considered candidates for SET.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.