Figure 1.

Study design. Schematic representation of the analyses of circulating vitamin B12 concentrations during foetal development and epigenome-wide DNA methylation in cord blood.

Abbreviations: adj: adjusted; cis-eQTM: cis-expression quantitative trait methylation; EWAS, epigenome-wide association study

* In this complete-case analysis, cohorts excluded participants with circulating vitamin B12 concentrations outside ± 5 standard deviations (SD) from the mean this complete-case analysis, cohorts excluded participants with circulating vitamin B12 concentrations outside ± 5 standard deviations (SD) from the mean of their study population, all twins, and in case of non-twin siblings, one child was excluded by selecting on completeness of data or, if equal, randomly. We prioritized CpGs with FDR-P-value <0.05 and showed low heterogeneity (I²<50%) for follow-up analyses. Vitamin B12, folate, and homocysteine were measured in either serum or in plasma.