Most common type of monozygotic twin pregnancy at 4th-8th day of cell division
In monozygotic twins, chorionicity depends upon time of cell division. Time of cell division Chorionicity of placenta First 72 hours post feilization(morula stage) DCDA 4-8th day(blastocyst stage) MCDA(MC type of monozygotic twins) 8-12th day MCMA >12th day Conjoined/Siamese twins, type of MCMA(fusion of embryonic disc occurs)
Monochorionic Monoamniotic twins with Siamese presentation
Monochorionic Monoamniotic(MO-MO) twins
Monochorionic Diamniotic twins(MO-DI)
Dichorionic Diamniotic twins (DI-DI)
Twin Pregnancy, Molar Pregnancy, Gestational Trophoblastic disease and contraception in special situations (Sour Grapes!)