Should the practice of double blastocyst transfer be abandoned? A retrospective analysis

As multiple pregnancy is now considered to be an adverse event of an IVF procedure, reducing the multiple pregnancy rates has become the goal of many IVF centres. A large number of double blastocyst transfers in non-selected patients were performed in the author's institution over recent years, and a retrospective analysis was conducted to investigate if multiple pregnancy rates in such a population are still unacceptably high. In addition, the factors determining the birth of singletons or multiple births following the transfer of two blastocysts was analysed. The live-birth rate per cycle was 35.7%, and the multiple-birth rate was 44.2% of all births. When clinically important variables that performed significantly in univariate analysis were analysed in the multiple regression model, age was negatively correlated with singleton and multiple births, and the transfer of two optimal blastocysts was positively correlated. Based on these results, abandoning the transfer of two blastocysts at least in patients younger than 37 years is recommended, regardless of embryo quality, as even the transfer of two non-optimal blastocysts results in almost 20% multiple births.