Statistic
Data analysis was performed with SPSS 21.0 software(IBM SPSS Statistics
for Windows, IBM, USA). Student’s t -test and Mann-WhitneyU -test were used to compare continuous variables with and without
normal distribution between the two group. The Chi-square and Fisher’s
exact tests were used for categorical variables. Cox survival regression
was conducted to compare the proportion of women undelivered after the
procedure.We used logistic regression to analyze risk factors associated
with adverse pregnancy outcomes. Differences were considered significant
when P < 0.05.