A baby who is born early (premature) is more likely to have or be vulnerable to health problems than babies born at full term and with a normal birth weight.

Babies born prematurely or at a very low birth weight have an increased chance for complications that lead to brain injury or abnormal development. The most common complications include:

• Bleeding within the brain (intraventricular hemorrhage, or IVH). It is most common in babies born prematurely or with a very low birth weight. Although the exact cause isn't well understood, it appears to be related to a premature baby's fragile blood vessels within the brain. These blood vessels easily rupture, which causes bleeding that can lead to brain injury. IVH almost always occurs within three days after a baby is born.
• Injury to the white matter of the brain, resulting in death and softening of some parts of the brain (periventricular leukomalacia, or PVL). Depending on its severity, PVL can result in varying degrees of abnormal development as a child grows and matures. PVL is thought to occur because of too little blood flow within areas of the brain either during fetal development, at birth, or during the first few days of life.
• Weighing less than 5.5 lb (2.5 kg) at birth may indicate existing health problems or make a newborn more likely to get infections or have problems that can affect brain development. Full-term babies sometimes have very low birth weights, although this occurs less often than in babies born prematurely.

Multiple-birth babies, such as twins, are more likely than single-birth babies to be born early or with a low birth weight. This also puts them at risk for poor health as newborns. These combined factors increase the risk of cerebral palsy.

Early signs of these types of complications include:

• Breathing problems.
• Low levels of thyroid hormone (thyroxine).
• Seizures.
• Low blood sugar levels.