36 - Preterm Labor and Birth

Abstract

Preterm labor precedes approximately 50% of preterm births. Preterm birth is the foremost problem in obstetrics and accounts for most perinatal death. Preterm birth occurs in approximately 12% of the approximately 4 million births in the United States. As such, there are more than 500,000 preterm births in the United States, and 15 million worldwide, each year. More than 75% of perinatal deaths related to preterm birth occur in infants born between 22 and 31 weeks of gestation. The rate of perinatal morbidity is also inversely proportional to gestational age at birth. The pathophysiology of preterm labor is not well understood. Preterm labor may occur as the common clinical presentation of intrauterine infection or inflammation, vascular insult, pathologic uterine overdistention, stress hormone activation, or other pathologic process. Preterm labor is a clinical diagnosis. Classically, the clinical diagnosis of preterm labor has been based on the presence of regular, painful uterine contractions accompanied by cervical dilation and/or effacement. Preterm labor is the clinical entity responsible for the majority of preterm birth, and its recognition and management can help optimize outcomes for mother and baby. Strategies such as maternal transport, antenatal corticosteroids, tocolysis, and magnesium sulfate for neuroprotection can help mitigate some of the clinical consequences of preterm birth due to preterm labor.