First of all, it is important to note that approximately half of twin deliveries occur by cesarean section. The key factor that will lead to one type of delivery or the other is the position of both babies. As there are two of them, it is more complex for both to be well positioned so that vaginal delivery can occur without complications and, for this reason, cesarean delivery is more common than in cases of single birth.
On the other hand, if it is a monochorionic monoamniotic pregnancy, a cesarean section will necessarily have to be performed. Since both babies are in the same placenta and the same amniotic sac, their umbilical cords are more likely to intertwine and lead to complications in vaginal delivery. Therefore, in these cases, cesarean section is usually performed.