Strengths and Limitations
This study was the first to establish nomogram for predicting PTB in patients with a short cervix. We describe predictors of PTB and their associated relationships. The key limitation of this study was that the sample size was not large. This could have affected the power of the effects observed. Although only 12 pregnancies was not clinically-indicated preterm births, the primary outcome of the study is PTB which could be classified into different subtypes according to clinical presentation including spontaneous preterm and clinically-indicated preterm births.