A multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple births are used, depending on the number of offspring.

Multiple birth siblings are either monozygotic or polyzygotic. The former result from a single fertilized egg or zygote splitting into two or more embryos, each carrying the same genetic material (genes).

Siblings created from one egg are commonly called........read more>>>>>>http://planehealth..com/2013/04/causes-effects-and-prevention-of.html