About nine percent of infants are born prematurely, or before the 37th week of gestation. While some of these babies are mature enough to survive without difficulty outside the womb, many need special care (which is usually given in a neonatal intensive care unit, or NICU) for at least their first few weeks.
Because they are not fully developed, premature babies frequently have problems with breathing, feeding, maintaining body temperature and fighting off infection. The smaller the baby is, the more serious these problems are likely to be. Babies who weigh less than 1,500 grams (three pounds and five ounces) at birth are most likely to develop complications of prematurity, but any infant weighing under 2,500 grams (five-and-a-half pounds) needs special attention. Because size is such an important factor in a newborn's health, pediatricians are alert to potential problems in any low-birth-weight infant (defined as one weighing under five-and-a-half pounds), whether the baby is born early or at term. With the care currently available, most premature babies do quite well.
WHAT CAUSES PREMATURITY?
In most cases, the direct cause of premature birth is unknown, but a number of factors are associated with it. Among them are premature rupture of the membranes (i.e., the mother's water breaks early), premature separation of the placenta (the mass of tissue that nourishes the fetus) from the womb's wall, and maternal infections, particularly of the uterus or urinary tract. Women carrying multiple fetuses, such as those who took fertility drugs or used assisted reproductive technology to conceive, have an increased chance of giving birth early, as do women under 17 or over 34 years of age. For unknown reasons, black women are twice as likely as white women to have low-birth-weight babies.
Problems in the fetus, such as organ malformations, are also associated with premature birth. In addition, premature labor occurs more frequently in women who have gained weight poorly during pregnancy or suffered severe nausea and vomiting. While most causes of low birth weight and prematurity are unknown, it is very clear that smoking, alchohol, drug use and poor nutrition in the mother significantly increase the risk of low birth weight and preterm birth. Pregnant women should do everything possible to avoid these risk factors.
Because prematurity is associated with complicated pregnancies and unhealthful habits, mothers of premature infants have a tendency to blame themselves for going into labor early. Actually, preterm labor seems to result from a combination of factors, the strongest of which are probably beyond the mother's control. Many women who have excellent health habits and trouble-free pregnancies still give birth prematurely.
HOW ARE PREMATURE BABIES DIFFERENT FROM TERM BABIES?
They are smaller, of course, with less body fat (one of the reasons it's harder for them to stay warm) and thin, shiny, almost transparent skin that is often covered with fine hair. Premature infants have soft skull bones that have not been rounded out by the full pregnancy process. Their heads appear a bit flattened, a problem that resolves itself in time but can still be distressing to parents.
They behave differently, as well. While term newborns lie with their arms and legs flexed and have some control over their movements, premature babies keep their limbs extended and relaxed. Premature babies also have poorly developed grasp, suck and gag reflexes. As a result, they often have trouble feeding.
The immaturity of premature babies' organ systems puts them at risk of serious complications. Some of these complications occur by themselves, but many are the result of some other problem. Many premature babies suffer from apnea, a periodic halt in breathing that seems to result from immaturity of the nerve pathways that control respiration. Incomplete development of the lungs leads to a complication called respiratory distress syndrome, which may require use of a mechanical ventilator and special medications to help the lungs work better. Immaturity of the immune system leaves premature infants vulnerable to many types of infection. In addition, premature babies sometimes develop neurologic conditions, such as cerebral palsy or bleeding in the area between the brain and skull, and some have permanently impaired vision due to a condition called retinopathy of prematurity. Because premature infants' livers are not fully developed, they often cannont handle the breakdown products of blood and become jaundiced (or hyperbilirubinemic). They may need treatment with phototherapy (lights) or exchange transfusions.
WHAT TYPES OF CARE DO PREMATURE BABIES NEED?
Premature babies need constant monitoring of breathing, heart function and body temperature with the special equipment available in NICUs. Many need extra oxygen or breathing assistance from mechanical ventilators.
They also may need tube feeding, since their energy requirements are high but they can take in little if any food by mouth. Those who can suck need lots of encouragement and frequent, small feedings. Premature babies can be fed either breast milk or formula. Since babies have more trouble nursing than drinking from a bottle, mothers who want to breast-feed usually express milk for bottle feeding until the baby gains some strength and coordination.
NICU nurses make frequent checks of each baby's appearance and monitoring equipment. They also listen to the heart, check blood pressure, look for changes in the baby's color and measure nutrient intake and stool and urine output.
Most premature infants lie in incubators, which are clear, plastic boxes with portholes in the sides for reaching in and handling the baby. Incubators are artificially heated to protect the premature infant from losing body heat; some types of incubators automatically adjust their temperatures in response to changes in the baby's temperature.
Several recent studies have suggested thant the round-the-clock noise, lights and activity in NICUs may not be good for premature babies. As a result, many hospitals now lower the lights, cover the cribs or incubators with blankets, and maintain a quiet environment with as little disruption as possible during the night. Others keep the lights on but cover the infants' eyes with pads to simulate darkness at night, and still others allow the babies complete rest for several periods each day. In addition, nurses, doctors and parents handle premature babies slowly and deliberately, since they are extremely sensitive to abrupt motion and other intense stimuli.
Researchers also have found that premature infants respond well to skin-to-skin contact. In some hospitals, parents are encouraged to massage their premature infants gently in the course of routine care, such as feeding, and a few hospitals are experimenting with a technique called kangaroo care, in which one parent holds the baby against his or her chest inside a pouchlike garment.
WHAT ARE THE LONG-TERM EFFECTS OF PREMATURITY?
For the first two to three years of life, most children who were born prematurely remain small for their ages, even though their growth rates are normal. While a few children born prematurely may have permanent problems, such as cerebral palsy and impairments in hearing and vision, the majority have no serious difficulties. The smaller and more premature a baby is, the greater are the chances of long-term effects.
COPING WITH PREMATURITY
Parents of premature infants face tremendous stress, especially if the baby has medical complications or spends a prolonged period in a NICU. Although NICU staffs try to involve the parents in as much of their baby's care as possible, it can be daunting for parents to assume total responsibility when their baby is ready to go home. The normal anxiety of new parenthood is compounded when parents must care for an extremely small, fragile infant who may have continuing medical problems. Here are some tips that may help:
• Even if your baby needs ongoing medical care, try to see yourself as a "regular" parent, especially after the baby comes home. Don't let clinical matter distract you from the joy of nurturing the new baby.
• Most premature infants are highly sensitive to stimulation; they turn away, become fretful or doze off after a brief period of handling. A slow, gentle approach will work best during feedings and other periods of interaction.
• Remember that premature infants' behavior matches their gestational age more closely than their calendar age. A baby born a month early, for example, may not do the things a full-term two-month-old does (such as smiling and head turning) until the third month of life.
