Positioning of the umbilical cord ahead of the baby's presenting part during labor and delivery. When this occurs, the baby's body puts pressure on the umbilical cord, which is caught between the baby and the mother's birth canal. This pressure can seriously reduce or altogether stop the blood flow through the umbilical cord.
Unless the pressure is removed through either delivery of the infant or repositioning of the infant, derious problems occur. Prolapsed umbilical cord offers more commonly with breech than with vertex presentation.