Statistical analysis
The normality of the variables was analyzed by Kolmogorov-Smirnov test
and Shapiro-Wilk test. For the variables that were approximately to
normal distribution descriptive statistics such as mean, standard
deviation and the range values were calculated. For non-normal data
median values were compared. Comparison of two group means were tested
using student independent test. Categorical variables were expressed in
terms of frequency and percent values. Logistic regression was used to
calculate crude odds ratios and adjusted odds ratios and their 95%
confidence intervals for each comorbidity as well as cardiovascular,
obstetric, fetal, delivery, and other events. We performed univariable
analysis at first, and multivariable logistic regression analysis was
performed for the variables with P < 0.1. For all analyses,
statistical significance was assigned based on a p-value
<0.05. All statistical analyses were conducted using SPSS
(IBM-SPSS Statistics v22.0, Inc. Chicago, IL) and R version 4.0.4 (R
Foundation for Statistical Computing, Vienna, Austria, 2021).