Health Problems of the Premature Infant

Infants born before 37 weeks' gestation are considered pre­mature. They often fall into the LBW category, defined as birth weight less than 2500 g. LBW and prematurity often go hand in hand. Most infants weighing less than 2500 g, and almost all weighing less than 1500 g, are premature. Mortality and morbidity are increased in the premature population and are inversely proportional to the length of gestation. The shorter the time of gestation, the greater is the risk for death or disability. The immaturity of the organ systems interferes with the successful transition to extrauterine life, predisposing this population to compli­cations. Included in this group are those premature infants who have grown abnormally during their shortened ges­tation (i.e., LGA or SGA). Abnormal growth places an added stress on their transition to extrauterine life.

Despite the advances in obstetric management since the late 1960s, the rate of premature delivery has not significantly changed. The incidence of preterm births (<37 weeks' gestation) has gradually increased since the mid-1980s from 9.5% to 11.6%. The cause of this increase is not known. African Americans are two to three times more likely to have a preterm delivery; almost one of every five African-American births is premature.²⁰ In the United States, LBW is responsible for two thirds of neonatal deaths despite an increase in the survival rate of the LBW infant. Contributing risk factors for prematurity also are asso­ciated with LBW. Risk factors associated with prematurity and LBW include maternal age (i.e., younger than 16, older than 35 years), race (i.e., African American more than white), socioeconomic status, marital status (i.e., single more than married), smoking, substance abuse, malnutrition, poor or no prenatal care, medical risks predating pregnancy, and medical risks in current pregnancy.^12,21

The premature infant is poorly equipped to withstand the rigors of extrauterine transition. The organ systems are immature and may not be able to sustain life. The respira­tory system may not be able to support gas exchange; the skin may be thin and gelatinous and easily damaged; the immune system is compromised and may not effectively fight infection; and the lack of subcutaneous fat puts the in­fant at risk for temperature instability. Complications of prematurity include respiratory distress syndrome, pulmo­nary hemorrhage, transient tachypnea, congenital pneu­monia, pulmonary air leaks, bronchopulmonary dysplasia, recurrent apnea, glucose instability, hypocalcemia, hyper-bilirubinemia, anemia, intraventricular hemorrhage, necro-tizing enterocolitis, circulatory instability, hypothermia,

bacterial or viral infection, retinopathy of prematurity, and disseminated intravascular coagulopathies.