A dizygotic (DZ) twin pregnancy is a type of twin pregnancy where two seperate ova are independantly fertilised by two seperate sperm resulting the two seperate zygotes. These twins are known as fraternal twins. They may or may not be of the same gender.
Dizygotic twins are the most common type of mulifetal pregnancy, accounting for approximately 70%. There is significant racial variation in incidence. The overall incidence is increasing due to the use of in vitro fertilisation.
A dizygotic twin pregnancy always results in dichorionic - diamniotic pregnancies. This feature alone cannot be used to distinguish dizygotic from monozygotic pregnancies as approximately 20% of monozygotic pregnancies will also be dichorionic - diamniotic.
Risk factors for dizygotic pregnancy :
- in vitro fertilisation (IVF)
- advanced maternal age
- family history
- ethnicity (e.g. Nigerian 3)
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