What is a Premature Infant?

A premature infant is a baby who is born too early, usually before 37 weeks of pregnancy. The normal span for human gestation is 40 weeks. Since vital organs in a premature infant, often called a preemie, are underdeveloped, the baby will need to stay in a hospital neonatal intensive care unit (NICU). Premature infant development involves the maturation of the baby's organs so that it can breathe, maintain body temperature and sustain vital functions in the absence of medical intervention.

Preemies usually weigh 5.5 pounds (2.5 kg) or less. They have low amounts of body fat and tend to have thin skin through which their blood veins can easily be seen. Sometimes, premature infants have hair on their bodies. They are less active and vigorous in their movements than babies born full-term. Premature infants also tend to have decreased muscle tone compared with full-term infants.

Often, a premature infant has trouble with feeding because its sucking reflex is not fully developed and because the baby cannot yet coordinate its breathing with its swallowing. Premature infant nutrition is provided in hospital NICUs either through intravenous (IV) feeding or tube feeding. The premature infant will receive nutrition in one of these ways until its development allows it to take food either by bottle or by breastfeeding.

A number of premature infant complications may arise. Preemies are vulnerable to infections. Some suffer from respiratory distress and are at risk for lung collapse. Breathing is sometimes irregular in premature infants, a problem known as apnea. Premature infants sometimes experience bleeding in their brains.

Many preemies remain at risk even as they develop. The earlier a baby is born and the lower its weight at birth, the more likely it is that the child will experience medical, developmental and behavioral issues that persist throughout its childhood and perhaps for the duration of its lifetime. Long-term effects may include delayed mental development, learning disabilities, or slow physical development. Some children born too early have dental, hearing or vision problems.

When a woman delivers a baby prior to 37 weeks of pregnancy, it is called a preterm birth. A number of medical conditions can contribute to a woman giving birth to a premature infant. Among them are abnormalities in the structure of the cervix or the uterus, bacterial infections of the genitals such as trichomoniasis, bacterial vaginosis and chlamydia, and chronic conditions such as lupus, diabetes or inflammatory bowel disease. Lifestyle issues are a concern, as well. Women who smoke, drink alcohol or don't get sufficient nutrition are at higher risk for preterm labor.