Abstract and Introduction
Abstract
Approximately 1 in 10 babies in the United States is born prematurely. Prematurity is the leading cause of death in newborns. Rates of morbidity and mortality are inversely related to gestational age or birthweight. Even infants born 2 or 3 weeks prematurely have an increased risk of death during their first year, compared with term infants. Premature infants suffer short-term and long-term consequences such as hypothermia, respiratory distress, cardiovascular disturbances, and increased hospitalizations, as well as visual, auditory, and learning disabilities. Drug therapy for common ailments affecting premature infants continues to evolve as new data become available.
Introduction
Infants born before 37 weeks' gestation are classified as premature. Prematurity is further delineated according to gestational age and birthweight (Table 1). Compared with term infants, premature infants have higher rates of morbidity and mortality, especially those who are extremely preterm (EPT) (<28 weeks) or extremely small (weight <1,000 g).
Of the nearly 4 million births occurring in 2011 in the United States, 11.7% were premature. This represents a 2% decline from 2010 (11.99%) and an 8% decline from 2006 (12.8%). The drop in premature births is commendable, but still higher than that reported in 1990 (10.62%). The percentage of EPT or very preterm (VPT) infants remained constant, whereas the percentage of infants born between 34 and 36 weeks' gestation increased from 7.3% in 1990 to 8.3% in 2011.
Preterm births are classified as iatrogenic (medically necessary), spontaneous, or secondary to premature rupture of membranes (PROM). From 1995 to 1996, spontaneous births accounted for 53% of preterm deliveries; iatrogenic births accounted for 33%. Recent data indicate a shift: From 2004 to 2005, spontaneous births accounted for 44% of preterm deliveries and iatrogenic births accounted for 47%. The rise in iatrogenic preterm births is attributed to an increase in late preterm births, although evidence suggests that not all are truly medically necessary.