Is there an increased risk of malformations after assisted reproductive technologies?

The question as to whether there is an increased risk of major malformations after assisted reproductive technologies has been answered insofar that it is slightly increased (30% relative risk when absolute figures analysed). This means an increased risk of 1:15 to 1:12 pregnancies when naturally conceived and intracytoplasmic sperm injection (ICSI) pregnancies are compared. Furthermore, there seems to be no risk difference between more invasive techniques (ICSI) or less invasive ones (conventional IVF). However, there are as yet no sufficiently robust data to describe the risk of children born either after ovarian stimulation only or intrauterine insemination procedures. With these data, it would be possible to clarify whether the increased risk after IVF and ICSI is due to the in-vitro culture techniques or to the ovarian stimulation procedure, or whether infertility per se is a risk factor. The latter seems to be suggested by retrospective studies. The different theories behind the increased risk of major malformations and the current database worldwide are described in this review.