Quadruplets Born: Quadrills are four offspring that were born at one birth. A person who is part of this set is referred to as fourfold and often fourfold.
Quadruples can be (multizygous), similar, or mixed. The fourfold can be fraternal. Four unique egg / sperm combinations include multizygous quadruplets.
A fertilized egg that breaks into two or more embryos results in monozygous multiples. A pause can be generated more than once, generating monozygous triplets or even some monozygous quadruples.
Fully monozygous quadruples are rare, representing only one pregnancy in approximately 13 million1.