It is a condition in which part of umbilical cord protrudes through the cervix either before or with the presenting part.

Types
Occult (incomplete) cord prolapse – the umbilical cord descends alongside the presenting part, but not beyond it.
Overt (complete) cord prolapse – the umbilical cord descends past the presenting part and is lower than the presenting part in the pelvis.
Cord presentation – the presence of the umbilical cord between the presenting part and the cervix occurring with intact membranes.