Figure legend
Figure 1. Flowchart of study cohort.
Figure 2. Logistic regression models for predictors of PTB
< 37 weeks and PTB < 34 weeks. PTB: preterm birth;
BMI: body mass index; IVF-ET: in vitro fertilization and embryo
transfer.
Figure 3. Profile of a nomogram to estimate risk of preterm
birth < 37 weeks (A) and preterm birth < 34 weeks
(B) in patients with a short cervix. Draw a line perpendicular from the
corresponding axis of each risk factor until it reaches the top line
labeled “Points”. Sum up the number of points for all risk factors
then draw a line descending from the axis labeled “Total Points” until
it intercepts the lower line to determine preterm birth probabilities.
For binary variables, 0 = no and 1 = yes. For BMI before pregnancy
categories, 0 = normal, 1 = overweight, 2 = obesity. Abbreviations: BMI
= body mass index.
Figure 4. Validation of the nomogram. (A) The AUC of the models
of PTB < 37 weeks and PTB < 34 weeks from observed
data (nomogram) was 0.803 and 0.771, respectively. AUC=area under ROC.
(B) Calibration curve for evaluating the agreement between the results
and the predicted possibilities of PTB < 37 weeks. (C)
Calibration curve for evaluating the agreement between the results and
the predicted possibilities of PTB < 34 weeks.