Holding 4

The Role of the Umbilical Cord in Pregnancy

It may look like a fairly insignificant 50cm piece of knobbly looking tissue coming out of what will be the baby’s belly button, but the umbilical cord is the one thing that links a developing baby to its mother, and is vital for keeping the baby alive while inside the uterus.

As well as tissue, the umbilical cord consists of two large arteries and a vein. One end is attached to the baby and the other to the placenta. The cord fans out to help form the placenta, which lies very close to the wall of the uterus, allowing transfer of material between mother and baby, while ensuring their blood doesn’t mix.

Through the placenta, oxygen and nutrients find their way into the baby’s circulation, while carbon dioxide and waste products travel the opposite direction to the mother and are excreted.

Blood flowing in both directions through this cord is absolutely essential in keeping the baby alive. Packed around the vessels is a supportive connective tissue called Wharton’s jelly, which gives the umbilical cord strength and support while protecting against folding on itself or getting tied in knots.

Some babies have very short cords, others very long ones. In up to one third of cases they can be wrapped around the baby’s neck, arms or legs at any time during the pregnancy or labour. For twins who share a single amniotic sac, the cords can become entangled and cause problems.

Normal movement inside the uterus can sometimes tie knots in the cord, which if pulled tight, can cause the flow of blood to stop and clots to form within the vessels, which can stop oxygen and nutrients getting through.

For the most part, the umbilical cord is a rich source of embryonic stem cells, which are immature, undifferentiated cells from the developing baby with the potential to turn into any type of body cells, from skin and nerve tissue to cells that make up the heart or kidney.

Research has been undertaken in how to best use these cells. They are currently only used in the treatment of childhood leukaemia, but potential uses include treatment of spinal-cord lesions, heart disease and brain illnesses. For this reason, some parents choose to save their baby’s cord blood in private or government cord-blood banks.


Dr Gino Pecoraro is an obstetrician and gynaecologist at the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, working in private and public practice in Brisbane.

Words by Dr G. Pecoraro

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