How do multiple births occur?
Multiple births occur more frequently after infertility treatment than in the normal population. About 80% of pregnancies achieved following simple ovulation induction with gonadotropins result in single births, the remaining 20% being multiple pregnancies, mostly twin pregnancies. New treatment regimens carefully adapted to the patient’s response help to decrease the risk of a multiple pregnancy. After IVF, one pregnancy out of four is multiple (20% twin pregnancies and 3-4% triplets). In IVF centers, physicians now frequently choose to replace a maximum of three embryos after fertilization, to further reduce the chance of multiple births.
