A Primer on Preemies

Premature infants, known as preemies, come into the world earlier than full-term infants. Prematurity occurs when a pregnancy lasts fewer than 37 weeks; full-term infants are born 38 to 42 weeks after they are conceived. Age in premature babies is often defined in postconceptional weeks (the number of weeks after the baby was conceived) until the baby is 40 weeks old, which is the average age of a full-term baby.

There are many causes of preterm delivery. Sometimes it's caused by the mother's lifestyle choices during pregnancy: smoking, drinking alcohol, using drugs, eating poorly, not gaining enough weight, exposure to physical stress, and poor prenatal care are all causes of preterm delivery. Often, however, the cause is not within the mother's control. The mother could have a hormone imbalance, a structural abnormality of the uterus, a chronic illness, an infection, or several other things that could lead to a premature birth. In addition, preterm delivery is more likely when a woman is over age 35, under age 19, or is carrying multiple fetuses. And sometimes the cause is simply unknown.

Premature infants have many special needs that make their care different from that of full-term infants, which is why they often begin their lives after delivery in a neonatal intensive care unit (NICU). The NICU is designed to provide an atmosphere that limits stress to the infant and meets basic needs of warmth, nutrition, and protection to assure proper growth and development. Due to many recent advances, more than 90% of premature babies who weigh 800 grams or more (a little less than 2 pounds) survive. Those who weigh more than 500 grams (a little more than 1 pound) have a 40% to 50% chance of survival, although their chances of complications are greater.

A Preemie's Basic Needs
Warmth
Premature babies lack the body fat necessary to maintain their body temperature, even when swaddled with blankets. Therefore, incubators or radiant warmers are used to keep the babies warm. Incubators are made of transparent plastic, and they Baby in incubator

completely surround an infant to keep him warm, decrease the chance of infection, and limit water loss. Radiant warmers are electrically warmed beds open to the air. These are used when the medical staff needs frequent access to the baby for care.

Nutrition and Growth
Premature babies have special nutritional needs because they grow at a faster rate than full-term babies and their digestive systems are immature. Neonatologists (pediatricians who specialize in the care of newborns) measure their weight in grams, not pounds and ounces. Full-term babies usually weigh more than 2,500 grams (about 5 pounds, 8 ounces), whereas premature babies weigh 500 to 2,500 grams.

What are premature babies fed? Breast milk is an excellent source of nutrition, but premature infants are too immature to feed directly from the breast or bottle until they are 32 to 34 postconceptional weeks old. Most premature infants have to be fed slowly because of the risk of developing necrotizing enterocolitis (NEC), an intestinal infection unique to preemies. Breast milk can be pumped by the mother and fed to the premature baby through a tube that goes from the baby's nose or mouth into the stomach. Breast milk has an advantage over formula because it contains proteins that help fight infection and promote growth. Special fortifiers may be added to breast milk (or to formula if breast-feeding is not desired), because premature infants have higher vitamin needs than full-term infants. Some premature babies receive additional vitamin supplements, too. The baby's blood chemicals and minerals, such as blood glucose (sugar), salt, potassium, calcium, phosphate, and magnesium, are monitored regularly, and the baby's diet is adjusted to keep these substances within a normal range.