Assessment of risk factors for preterm delivery

Preterm birth is one of the leading causes of neonatal mortality and morbidity, and preterm labor, preterm premature rupture of membranes, and vaginal bleeding are the most common clinical signs announcing preterm birth. Until now screening strategies have failed to reliably identify those women who will have a preterm delivery. There are no current data available to support the use of salivatory estriol, maternal serum CRH, home uterine activity monitoring, or bacterial vaginosis screening as strategies to identify, let alone to prevent preterm birth. Screening for a risk of preterm labor by means other than historic risk factors is not beneficial in the general obstetric population. Sonographic cervical assessment, and fetal fibronectin testing, or a combination of both may be useful in women at high risk because of a previous preterm birth or in women with symptoms of preterm labor to identify those with negative values and thereby to avoid unnecessary interventions. Given the lack of proven treatment options to prevent preterm birth, the major clinical usefulness of screening strategies may rest primarily with their negative predictive value.