 Transvaginal ultrasound of the cervix has become a common tool to evaluate patients who are at risk for preterm delivery. A shortened cervical length has been associated with an increased risk of preterm delivery. Dynamic cervical change is visible shortening6mm of the cervix seen during the ultrasound examination. Prior studies have shown that the presence of dynamic change in patients with a shortened cervical length3cm is not independently predictive of preterm delivery. However, a subset of patients with normal initial cervical length3cm and dynamic change did demonstrate an increased rate of preterm delivery. Because this was a small sub-group, the present study was designed to obtain a larger sample size for further evaluation. The second focus of this study involves patients with a dilated cervix and whether cervical length adds predictive value to gestational age at delivery. 