Eating for Two

Babies in the womb can see, hear and move around. But they can’t eat, drink or breathe. Instead they rely on a constant supply of oxygen and nutrients from their mother, which passes through a specialised disc-shaped organ – the placenta (pictured). This is the growing embryo’s lifeline, which starts to develop as soon as an embryo attaches to the wall of the womb, and grows with the baby. This is a fully developed placenta, which measures about 22cm across and weighs about half a kilo. It’s full of blood vessels and spongy tissue, which allow gases and nutrients to be exchanged between mother and child. Nourished blood passes to the baby via the umbilical cord, which can be seen in the centre. When a baby is born, the placenta detaches from the womb and is usually expelled about half an hour afterwards. The cord is then cut to separate them.

• Alexander Heazell
• University of Manchester
• Originally published under a Creative Commons Attribution license
• PLoS ONE 7(4): e34851