Preterm Labor

Preterm Labor

Preterm birth is delivery that occurs prior to theP completion of 37 weeks (259 days) of gestation.

Because it is the most common cause of perinatal morbidity and mortality in the United States, prevention and treatment of preterm birth is a major focus of obstet-ric care. 

The consequences of preterm birth occur with increasing severity and frequency the earlier the gesta-tional age of the newborn. In addition to perinatal death in the very young fetus, common complications of preterm birth include respiratory distress syndrome, intraven-tricular hemorrhage, necrotizing enterocolitis, sepsis, neurologic impairment, and seizures. Long-term mor-bidity associated with preterm delivery includes broncho-pulmonary dysplasia and developmental abnormalities, including cerebral palsy. The 11% to 12% of babies bornprematurely account for 75% of all perinatal mortality and 50% of long-term neurologic impairment in children in the United States.

Preterm births may be classified into two general pre-sentations: spontaneous and indicated. Approximately 40% to 50% of preterm births result from spontaneous preterm labor with intact membranes; 25% to 40% result from preterm premature rupture of membranes (PROM). The remaining 20% to 30% occur following deliberate inter-vention for a variety of maternal or obstetric complica-tions (e.g., eclampsia).

Preterm labor is defined as the presence of regular uter-ine contractions that occur before 37 weeks of gestation and are associated with cervical changes. It is often difficult to diag-nose preterm labor because of the absence of definitive measurements. The lack of diagnostic criteria presents a problem, because treatment appears to be more effective when initiated early in the course of preterm labor