Differences in means of continuous variables by treatment for mother’s baseline characteristics were determined using
analysis of variance; differences in categorical variables by treatment were analyzed using contingency table analyses and associated chi-square tests or Fisher’s exact test when expected counts were low. Differences in children’s baseline characteristics by treatment were analyzed using linear mixed models for continuous variables and logistic regression analyses in the context of generalized estimating equations(31)for categorical variables,to allow adjustment for correlation between siblings. Baseline characteristics found to be significantly different were adjusted for in subsequent analyses.