According to many reports multiple pregnancies compared to singelton have a 5-10 fold increased risk for CP and some of increased risk is due to the risk of preterm delivery, no mater whether, it mono or dizygotic conception. In those cases CP is most probably complication of peripartal periventricular hemorrhage or leukomalacia. Known fact about twins is that the lower is the gestational age at the time of delivery, the probability that they are monozygotic is greater. Monochorionic multiple pregnancies and feto-fetal hemodynamic transfusion instability are leading to cerebral ischemia. For all of mentionable reasons monozygotic multiple pregnancies have a greater risk of cerebral impairment.

CP in an apparently singleton pregnancy could be associated with a “vanishing” twin phenomenon. There are reports that some of the congenital anomalies in apparently singleton pregnancies may be associated with the unrecognized or unrecorded loss of a co-twin.

It has been established that ART conceptions are at a greater risk of CP because of the greater risk of preterm delivery. There have been many attempts to minimize CP prevalence by reduction of number of fetuses in a multifetal ART pregnancy but without affect, most probably because the majority of ART conceptions are dizygotic.