The Preterm Labor Syndrome

Prematurity is the leading cause of perinatal morbidity and mortality worldwide.' It affects 5-10% of births. Preterm neonates have a 120 times higher risk of death than term neonate^.^-^ Survivors are at risk for short-term and long-term morbidity, which includes bronchopulmonary dysplasia, blindness and psychomotor retardati~n.~-]O The prevention of premature birth is the single most important challenge to modern obstetrics today. Progress in this area has been hampered by lack of understanding of the basic mechanisms responsible for premature labor and delivery. The implicit paradigm which has governed the study of preterm parturition is that term and preterm labor are fundamentally the same processes except for the gestational age at which they occur. Indeed, they share a common terminal pathway composed of uterine contractility, cervical dilatation and rupture of membranes. I ' We propose that the fundamental difference between term and preterm labor is that the former results from physiologic activation of the components of the common terminal pathway while preterm labor results from a disease process which extemporaneously activates this common terminal pathway. This article will review the evidence that preterm labor is a pathologic condition caused by multiple etiologies, and hence should be considered a syndrome: the Preterm Labor Syndrome.