2.5. Statistical Analysis
obesity
OBESITY, REGRESSION, ADVERSE EFFECT
Descriptive statistics are presented as number (n) and percentages (%) for categorical variables and n, mean and standard deviation (SD) for continuous variables. We provide descriptive statistics for the baseline covariates, total fibre intake, and main fibre food sources at each time point. A comparison of fibre intake and obesity outcomes between intervention and control groups revealed no statistical difference. Therefore, data from the intervention and control groups were pooled for the present analysis, and intervention allocation was included as a covariate.Group-based trajectory modelling was used to identify trajectory groups of fibre intake from ages 9 to 60 months using the “Traj” command in Stata. Individuals with fibre intake measured at one or more time points over the four time points were included. Analyses were also conducted for children with two or more fibre intake measurements (n = 420) and showed similar results (Multivariable logistic regression models were performed to examine the association between child and maternal predictors of fibre trajectory groups. Given the high prevalence of low fibre intake in children and the adverse effect of low fibre intake on health, determinants of low fibre intake trajectory were assessed. Other trajectory groups were combined and analysed as the low fibre intake trajectory reference category. The following determinants were assessed: child sex, birth weight, breastfeeding duration, the timing of solid food introduction, maternal employment status, education, country of birth, and pre-pregnancy body weight status. Multi-collinearity between these factors was examined, and no significant correlation was found.We conducted a multivariable linear and logistic regression model to examine the association of fibre trajectory groups with child BMI z-score and overweight status at age 60 months, respectively. In model 1, we adjusted for BMI z-score at age nine months; in model 2, we additionally adjusted for the treatment group, child sex, breastfeeding duration, timing of solid food introduction, maternal employment status, education, country of birth and pre-pregnancy BMI; and model 3 additionally adjusted for energy intake at age nine months. As children transition from a milk-based diet to a food-based diet by age one year, sensitivity analyses excluding the 9 months old fibre intake data were conducted.All statistical analyses were performed using Stata version 15 (StataCorp. 2017. Stata Statistical Software: Release 15. College Station, TX, USA, 