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.