In recent years, the increased use of assisted reproduction techniques to achieve pregnancy has led to an increase in the number of twins due to the fact that these techniques are accompanied by a process of prior ovarian stimulation and also by the embryo transfer of, on many occasions, more than one embryo.
However, this does not mean that all twins come from assisted reproduction or that all fertility treatments result in twin pregnancies.
Naturally, twin births (identical twins or twins) occur in 1.5% of cases. In contrast, by artificial insemination (AI) the rate of this type of birth is 8.8% and in vitro fertilisation (IVF) is 8.4% per transfer, taking into account the latest statistical record of the Spanish Fertility Society for 2022.
The statistical data shown here should not be used to imply or predict a certainty of outcome for a specific individual within an at-risk population.
