Probability of identical twins by in vitro fertilisation

Even if a single embryo is transferred, there is a possibility, albeit low, that it may split in two to produce two identical embryos. In the event of both implanting, an identical twin pregnancy would result.

This naturally occurs in 0.4% of pregnancies. In IVF-ICSI cycles, on the other hand, an increase of 1.5-2% in this probability has been seen, so that such a pregnancy could occur in 1.9-2.4% of cases.