Assisted Reproduction and Discussion of Rare Cases in Monozygotic Twinning.

Assisted reproductive technology is a crucial factor that increases the incidence of monozygotic twinning in humans. This article discusses the impact of various indicators in assisted reproductive technology studies on pregnancy outcomes, especially studies with a large number of clinical cases. Furthermore, three rare cases in multiples pregnancy are discussed: fetus papyraceous of a pair of male monozygotic twins in a set of triplets, two pairs of sesquizygotic twins with sex-discordance, and rare conjoined triplets.