Figure 1.

Magnesium concentrations in healthy pregnant women without magnesium supplementation during pregnancy. * If 95% CIs were not reported in the study, then the 95% CIs were calculated as follows: mean ± (1.96 × SD). ^† Patient groups within these studies were pooled, as the literature search did not confirm an association between magnesium levels and gestational age, birth weight, or mode of delivery. ^‡ Reference line and 95% CI derived using only studies reporting both mean and SD data. Overall statistic for heterogeneity: I² = 97.8% (p < 0.001). CI: confidence interval, SD: standard deviation.