Main Findings
In pregnant women with a short cervix in this study, variables identified as predictors of PTB <37 weeks included overweight or obesity, frequency of pregnancy (≥3 times), twin pregnancy, IVF-ET, gestational age of at first diagnosis of short cervix (1st short cervix), gestational age of at first diagnosis of short cervix (1st short cervix), history of PTB, and autoimmune disease. On the other hand, twin pregnancy, gestational age of 1st short cervix, CL of 1st short cervix, history of PTB, and prepregnancy hypertension were identified as predictors of PTB < 34 weeks. Nomogram of PTB < 37 weeks and PTB < 34 weeks showed good discrimination and agreement, thus can be used in obstetrics to identify patient at risk of PTB, especially those first diagnosed with a short cervix.