Premature Babies

Preterm birth is defined medically as birth of an infant after viability has been achieved with gestation of at least 20 weeks or birth weight of at least 500 g but before 37 weeks.

Most pregnancies last about 40 weeks. About 12 percent of babies in the United States, or one in eight are born prematurely each year. In 2003, more than 490,000 babies in the United States were born prematurely.

Worldwide rates of prematurity are more difficult to obtain as the lack of widespread professional obstetric care in developing regions makes determination of gestational age less reliable. The World Health Organization instead tracks rates of low birth weight, which occurred in 16.5 percent of births in less developed regions in 2000. It is estimated that one-third of these low birth-weight deliveries is due to prematurity.

Infants born prematurely have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10 percent of neonatal mortality, or around 500,000 deaths per year. In the United States, where many of the infectious and other causes of neonatal death have [Page 1418]been markedly reduced, prematurity is the leading cause of neonatal mortality at 25 percent.

The shorter the term of pregnancy, the greater the risks of complications. Prematurely born infants are also at greater risk for developing serious health problems such as cerebral palsy, chronic lung disease, gastrointestinal problems, mental retardation, and vision and hearing loss.

Although there are several known risk factors for prematurity, nearly half of all premature births have no known cause. When conditions permit, doctors may attempt to stop premature labor, so that the pregnancy can have a chance to continue to full term, thereby increasing the baby's chances of health and survival. However, none of these methods have been proven to be too reliable, as in fact, the rate of preterm births in the United States has actually increased 30 percent in the past two decades.

Some newer research has identified possible methods to prevent preterm birth, pre-eclamp-sia/eclampsia, premature rupture of membranes, and preterm labor. This research includes self-care methods to reduce infections, nutritional and psychological interventions, and the control of preterm birth risk factors (e.g., working long hours standing on feet, carbon monoxide exposure, domestic abuse, and other factors). This research is quite new; however, doctors using these newer strategies have obtained preterm birth rates as low as 1 to 2 percent, compared to the 11 to 16 percent currently in the United States. In developed countries, premature infants are usually cared for in a special section of the hospital known as the neonatal intensive care units (NICUs). The physicians who specialize in the care of very sick or premature babies are known as neonatologists. In the NICU, babies are kept in incubators (also called isolettes), which are bassinets enclosed in plastic with climate-control equipment designed to keep babies warm and limit their exposure to germs.

Modern neonatal intensive care involves sophisticated measurement of temperature, respiration, cardiac function, oxygenation, and even brain activity. Treatments may include fluids and nutrition through intravenous catheters, oxygen supplementation, mechanical ventilation support, and medications.

...