What is a Premature Birth?
A PREMATURE BIRTH, occurs when a woman gives birth to a baby before the end of the normal period of pregnancy. The normal period of pregnancy ranges from 37 to 42 weeks after a woman begins her last menstrual period prior to becoming pregnant. Births that take place between 20 and 37 weeks of pregnancy are said to occur preterm. At one time, a birth weight of less than 5 1/2 pounds (2.5 kilograms) was the only measure for determining prematurity. Today, it is understood that a baby can weigh more than 5 1/2 pounds and still be functionally immature, while an infant of less than 5 1/2 pounds can be functionally mature. Most premature infants that weigh more than 3 1/3 pounds (1.5 kilograms) at birth grow up as healthy as babies born after a normal pregnancy. Premature babies weighing less than 2 1/5 pounds (1 kilogram) at birth have the poorest chance of survival.
In many premature infants, certain organs--especially the lungs--have not developed sufficiently for the baby to survive without medical assistance. Hyaline membrane disease, also called respiratory distress syndrome, ranks among the most serious lung disorders that strike these babies. Some infants with this condition are attached to a respirator (see HYALINE MEMBRANE DISEASE). Other common problems include the inability to digest normal-sized feedings and the body's lack of adequate control over its temperature. If the baby can suck and swallow, special formulas may be given by bottle. Some premature infants must be fed by means of a tube passed through the nose and into the stomach. Others may need to be fed entirely through a tube inserted into a blood vessel. Most premature infants are placed in an incubator to assure a constant body temperature.
Premature births occur least frequently among healthy women who receive periodic medical care. A woman can help assure a normal birth by following a well-balanced diet and by avoiding the use of tobacco, alcohol, and all drugs except those recommended by her physician. In the United States, about 7 per cent of white babies and 14 to 15 percent of nonwhite babies are born prematurely. The cause of preterm births are still poorly understood. A variety of factors involving the mother, the unborn baby, and the placenta an organ that develops during pregnancy, joining the mother and the unborn baby can result in preterm delivery. Many women who give birth prematurely have a medical condition associated with premature birth. Such conditions include abnormalities of the uterus, drug addiction, high blood pressure, and being pregnant with more than one baby. A woman who has had a premature baby or a miscarriage has about a 20 per cent chance of again giving birth prematurely. Scientists have developed a number of drugs that can help stop preterm labor before it results in premature birth.
Contributor: Lois Kazmier Halstead. Source: World Book.