Brain bleeds are especially dangerous because as leaking blood fills up space, the skull cannot expand and the brain is compressed. With enough bleeding, the brain gets compressed so much that oxygen-rich blood is prevented from flowing into the brain tissue. This lack of oxygen causes additional brain swelling.
There are two types of oxygen deprivation that can cause problems for a fetus or infant during (or after) delivery: Hypoxia and anoxia. Both are potentially life-threatening medical conditions that need to be quickly identified and corrected because when oxygen levels become too low brain damage and death can occur.