This is the process of given nutrition directly into the bloodstream. It is often referred to as TPN or total parenteral nutrition. The solutions contain sugars, proteins, fats and vitamins ? everything the baby needs to grow. Parenteral feeding solutions are often given through a central line, also known as a long line.

The most common problem for very premature babies is that a small connection between the vessels supplying the lungs with blood and the vessels supplying blood to the body remains open. Doctors call this patent ductus arteriosus

Pressure applied during breathing out. This helps to prevent the lungs from collapsing while the baby is on the ventilator.

When pauses of up to 10 seconds take place in the baby's breathing.

If parts of the developing brain are deprived of oxygen and blood flow for too long, the brain cells may die and be replaced by fluid cysts. These can be seen in ultrasound scans of a baby's brain. Depending on the area affected, PVL may indicate future developmental problems.

Before birth, the blood vessels of the lung are narrow. If the blood vessels do not relax after birth, blood flow to the lungs is reduced. Oxygen, and sometimes drugs, are given to open the narrow vessels.

This is about the acidity (low value) or alkalinity (raised value) of the blood. A value close to 7.4 is normal for arterial blood.

Using blue (not ultraviolet) light to reduce the bilirubin level (also see 'Jaundice').

Special exercises to improve or relieve physical problems.

When there is air between the lung and chest wall if a lung has leaked air.

When the baby spits up a small amount of milk after feeding.

This occurs in about one in 14 pregnancies and causes around a third of all premature births. It can be dangerous, particularly if it develops rapidly. The main symptoms are headaches and swollen feet, which are associated with high blood pressure. Although bed-rest can help, the only way to stop pre-eclampsia is to deliver the baby early.

A baby born before reaching 37 complete weeks in the womb is premature.

Also known as a saturation monitor. This is used to monitor the amount of oxygen in the baby's blood. It is very sensitive and often sounds an alarm even though the baby may be OK. It works by shining red light through the hand or foot. From the amount of light absorbed, the oxygen levels can be established.