Since the first live birth resulting from in vitro fertilization (IVF), there has been a dramatic rise in the number of infants born as a result of this technology. Assisted reproductive technologies (ART) are now widely used in the treatment of human infertility. It is likely that well over 1 million babies have been born worldwide using ART. The majority of perinatal morbidity after assisted reproductive technology is due to multiple pregnancies. In United States and Europe even 30% of twins are conceived by IVF, intracytoplasmic sperm injection (ICSI), or frozen embryo replacement (FER). ART carries a significantly increased risk of multiple pregnancies, which are associated with a higher rate of prematurity and low birth weights, and carry well‑established risks of morbidity to the child. Many recent studies have suggested also that even singleton pregnancies are at increased risk for preterm birth, low birth weight, congenital anomalies, perinatal mortality and several other pregnancy‑related complications. In addition, it has been shown that the infertility characteristics of the parents may influence the perinatal outcome. Finally, procedural factors related to fertility treatments themselves may confer health risks to ART children. These include the artificial induction of ovulation with the possibility of changes in follicle milieu and oocyte structure, exposure of sperm and embryos to in vitro environments which might change their natural function, freezing and manipulation of oocytes and embryos.