Statistical analysis
Logarithmic10 transformation of variables was performed prior to statistical analysis, when necessary, then the Kolmogorov-Smirnov test was used to determine whether the data were parametric. Parametric continuous variables were presented in mean and standard deviation (SD) while nonparametric continuous variables were presented in median and interquartile range (IQR). Count and percentage were used to present categorical variables. The following variables were reported as z-scores corrected for gestational age: EFW, birth weight, UA-PI, MCA-PI, CPR, and UtA-PI. Relationship between EFW z-score, UA-PI z-score, MCA-PI z-score, CPR z-score, UtA-PI z-score, log10 cCTG STV, and umbilical cord arterial pH was determined using Pearson correlation analysis. To determine which of the maternal characteristics, labour onset, indications of induction of labour, EFW z-score, maternal-foetal Doppler indices, log10 cCTG STV, and Dawes-Redman criteria were significant predictors of umbilical cord arterial pH, univariate linear regression analysis was used. To identify the variables that were independent predictors of umbilical cord arterial pH, predictors with a p value of < 0.1 were included in a multivariate linear regression analysis with forward selection. Univariate and multivariate logistic regression analyses were used to determine whether which of the study factors mentioned above were significant predictors of umbilical cord arterial pH < 7.1 and NICU/SCBU admission. The statistical software package SPSS 20.0 (IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp) was used for data analyses.