Abstract
Since the first in vitro fertilization (IVF) baby was born in 1978, more than 1 million children have been born following assisted reproductive technology. During the 1990s, most European countries succeeded in reducing the incidence of triplet births; however, due to the double embryo transfer policy, twins still account for over 20% of the assisted reproductive technology children born. It is well known that the outcome of twins is poorer than for singletons; however, another consequence of double embryo transfer is that one in ten IVF singletons are born after a vanishing twin pregnancy. Two-thirds of these lose their co-twin during the first and second trimester, but even if spontaneous reduction onsets early in pregnancy this influences the survivor, as the surviving fetus carry higher neonatal risks including low birthweight, preterm birth, intrauterine growth retardation, neonatal deaths and admission to neonatal intensive care unit. Presumably, long-term outcomes such as cerebral palsy are also increased with higher prevalence the later in pregnancy the co-twin disappears. Hence, by implementing single embryo transfer to good-prognosis IVF patients we will benefit not only from reduced twin birth rates but the outcome of IVF singletons will also improve.
Financial & competing interests disclosure
The author has 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.