Wulff CB, et al. - Cervical length (CL) was assessed longitudinally between the first and second trimesters and the proportion of women with short CL were determined. Whether or not women with short CL at 19–24 weeks' gestation could be identified at the time of combined first-trimester screening (cFTS) at 11–14 weeks' gestation was assessed, in order to determine the potential value of implementation of CL screening for prediction of preterm delivery in a Danish population. First-trimester CL was observed to have an association with the risk of short cervix in the second trimester. Risk of preterm delivery was greatly increased with short CL identification.