Maternal serum 25-hydroxyvitamin D (25(OH)D) concentration, by time or cumulative dose of vitamin D3. Thick lines represent the negative exponential model-predicted serum 25(OH)D concentrations as a function of time (A) and as a function of cumulative dose of vitamin D3 (B). Thin solid lines represent the 95% confidence interval (95% CI) around the predicted 25(OH)D. In panel B, all placebo group data are clustered at 0 mcg given the lack of vitamin D3 supplementation. Model fit as assessed by R2 was 0.75 in both panels A and B.
Roth et al. Nutrition Journal 2013 12:47 doi:10.1186/1475-2891-12-47