Statistics
The sample size was based on the trial primary outcome of gestational glycemia, as described previously [For each of the vitamins and related vitamers and metabolites, analyses focused on (i) describing the longitudinal changes in maternal concentrations from preconception through pregnancy and to 6 months postdelivery in the control group, (ii) the pattern of longitudinal change in the intervention group, and (iii) differences in concentration and in sufficiency markers between the control and intervention groups at different time points, including differences in proportions analyzed using chi-squared tests. Longitudinal plots are shown as means and 95% confidence intervals (CI; calculated using the exact method for continuous outcomes and binomial exact method for proportions) in SDS by intervention group on y-axis and time point/visit on x-axis, with statistical significance considered when the 95% CI did not overlap (two-tailed 