Predictive factors associated with SPTB at < 32 weeks
In the training group, we conducted univariate and multivariate
regression analysis to detect the correlations between clinical
variables and probabilities of preterm delivery before 28 weeks, 32
weeks, and 34 weeks by applying the AIC-based backward procedure
repectively (Table 1). Then we constructed three ROC curves for
predicting SPTB according to the results of multivariate analysis. By
comparing the AUCs, we found that the predicted value for SPTB at
< 32 weeks was the highest (Supplementary Figure 1). After
comprehensively considering the predictive power and the number of
positive cases of PTB before the there gestational weeks(the number of
positive cases who delivered before 28 weeks was significantly less than
10 times that of multivariate meaningful variables), we finally chose to
establish a predictive model for predicting PTB at < 32 weeks.
Multivariate logistic regression analysis (<32 weeks) showed
that
nulliparity,
monochorionicity, prepregnancy BMI, previous preterm birth or late
abortion, cervical funneling and shorter cervical length were
independent risk factors for SPTB at < 32 weeks.