<unk>  is a rare complication of multiple pregnancy where two fetuses become interlocked during presentation before birth. It occurs in roughly 1 in 1,000 twin deliveries and 1 in 90,000 deliveries overall. Most often,<unk>  are delivered via Caesarean section, given that the condition has been diagnosed early enough. The fetal mortality rate is high for the twin that presents first, with over 50% being stillborn.
Locked twins
Conjoined twins
Vanishing twin
Monochorionic twins
Monoamniotic twins
Vestigial twin
Parasitic twin
Coffin birth