Umbilical cord prolapse is a rare but serious childbirth complication in which the umbilical cord slips through the cervix ahead of the baby after the waters break. It is a medical emergency because the cord can be squeezed.
The umbilical cord carries oxygen and nutrients from the placenta to the baby. When the cord slips down in front of the baby, it can be pressed by the baby's body or by contractions. This pressure can reduce the baby's oxygen supply, so the baby needs to be born quickly.
Cord prolapse is uncommon. The RCOG estimates it happens in between 1 in 200 and 1 in 1000 births, usually close to the end of pregnancy. The risk is higher when the baby is breech or lying sideways, in twin pregnancies, with premature birth, with a lot of amniotic fluid, or when the waters break before the baby's head has moved down into the pelvis.
The care team works to take pressure off the cord, for example by changing the mother's position or gently lifting the baby's head. The baby is then delivered as fast as possible, often by emergency cesarean section. If you are at home and feel or see the cord after your waters break, call emergency services immediately.
Doctors cannot predict every case, but people with known risk factors may be advised to come to hospital as soon as their waters break or to stay in hospital near the end of pregnancy. A midwife or obstetrician will explain any personal risk.
Sources: RCOG, MedlinePlus.