Statistical analysis
Continuous variables were described by mean ± standard deviation (SD).
Categorical variables were described by counts and percentages
(%).Prenatal and neonatal outcomes of three groups were compared using
the Chi-square test for categorical variables, and Student’s t-test for
continuous variables. We estimated the risk ratios (RRs) and 95% CIs
for categorical adverse pregnancy and neonatal outcomes using Modified
poisson regression model. In a few instances, the models did not
converge and Firth’s bias-reduced penalized-likelihood logistic
regression was used. Also A linear mixed effect model was used to
analyse changes in continuous adverse pregnancy and neonatal outcomes.
The models were adjusted for the following potential confounders:
gestational age, parity, body mass index, maternal age, previous
caesarean section, previous pregnancy problems, pre-existing medical
problems, and mode of delivery. Statistical analyses were performed on
Stata16.0 (Stata Corp, College Station, TX, USA). All statistical tests
were two-tailed at the significance level of P < 0.05.