Abstract: The incidence of monozygotic twinning raised after the assisted reproductive technology（ＡＲＴ） was used for infertility treatment. Although the detailed mechanism is not well?-known, the increased monozygotic twinning rate after ART may be related with ovarian stimulation, injury of zona pellucida, changes in culture media and multiple embryos transfer. Twin?-twin transfusion syndrome is the most serious complication, so it is important for monozygotic twinning to early diagnosis and early treatment. In recent years, doctors of reproductive medicine and obstetricians have paied more attention to monozygotic twinning. We reviewed the factors of the raised incidence of monozygotic twinning after ART, as well as diagnosis and prognosis of monozygotic twinning.

Key words: Twins, monozygotic, Fertilization in vitro, Embryo transfer, Reproductive techniques, assisted