Preterm Labor Prediction by Cervical Contour in Ultrasound

Cervical length is a already known predictor for preterm labor. In this study the investigators want to examining the hypothesis that cervical curvature is also a predictor for preterm labor and that moderate transducer pressure influence cervical length. study population: 200 consecutive pregnant women between 14-34w, visiting in the ultrasound unit ether for routine screening or because of preterm labor. During their examination cervical length and curvature measurements will be taken. Another measurement will be taken after applying moderate cervical pressure. The investigators will compere cervical contour and pressure influence between groups and according to cervical length Demographic data will be taken at the time of recruitment and pregnancy outcome measures in a later telephone interview.