Premature babies have immature organs. The brain, eyes, kidneys, lungs, intestines are all not fully mature. As maturity occurs the tissues become stronger and the blood vessels bleed less easily. In a premature baby bleeding can occur in the brain or in the lungs or in any of these organs. Once the bleeding starts in either the lung or the brain it is almost impossible to control it and therefore pulmonary haemorrhage as well as brain haemorrhage are catastrophic events.