Figures & data
Figure 1. Venn diagram showing the number of CpG sites that demonstrate differential methylation when comparing groups. Differential methylation is defined as a mean absolute methylation level difference > 2% and significance was tested by using a two-group Students t-test (for nulligravid vs. either early pregnant or postpartum), or paired t-test (early pregnant vs. postpartum), after correction for multiple comparisons with FDR < 0.1. The power of the pair-wise comparison is demonstrated by the large number of significant CpG sites in the pregnant vs. postpartum comparison, as contrasted with the pregnant vs. nulligravid comparison. There were 9 genes differentially methylated in the early pregnant vs. postpartum state, which were also differentially methylated in the early pregnant vs. nulligravid state
Figure 2. A volcano plot illustrating the global methylation differences between pregnant and postpartum samples. Each dot represents a comparison of mean methylation at an individual CpG site. The x-axis is the methylation mean difference (pregnant - postpartum). The two dashed lines delineate minus 2% and plus 2% methylation mean difference. The y axis is the negative Log10 of the p value; dots in red have an FDR q value < 0.1, those in green have a p value < 0.05, and black sites have non-significant differences. Note the large number of highly significant differentially hypomethylated sites in pregnancy (arrow).
