Table 3. . Associations of prenatal socioceonomic status with global DNA methylation (%5mC), hydroxymethylation (%5hmC) and the ratio of global DNA methlyation to hydroxymethylation (%5mC:%5hmC) among Project Viva participants at birth, during early childhood (median age 3 years) and mid-childhood (median age 7 years).

Prenatal SES§	N	β (95% CI)† in cord blood DNA methylation (birth)
		% 5mC	% 5hmC	% 5mC: % 5hmC ratio‡
		Mean (SD) = 5.67 (2.07)	Mean (SD) = 0.25 (0.15)	Mean (SD) = 4.67 (0.70)
Lowest 10%	45	-0.44 (−1.08, 0.20)	0.00 (-0.05, 0.04)	−0.05 (-0.26, 0.17)
Upper 90%	368	0.00 (Reference)	0.00 (Reference)	0.00 (Reference)
p-value		0.18	0.86	0.66
	N	β (95% CI)† in peripheral leukocyte DNA methylation during early childhood (∼3 years)
		%5mC	% 5hmC	%5mC:%5hmC ratio‡
		Mean (SD) = 5.11 (1.77)	Mean (SD) = 0.17 (0.11)	Mean (SD) = 5.10 (0.75)
Lowest 10%	9	-0.28 (-1.46, 0.91)	0.02 (-0.06, 0.10)	-0.32 (-0.86, 0.22)
Upper 90%	94	0.00 (Reference)	0.00 (Reference)	0.00 (Reference)
p-value		0.64	0.57	0.25
	N	β (95% CI)† in peripheral leukocyte DNA methylation during mid-childhood (∼7 years)
		%5mC	% 5hmC	%5mC:%5hmC ratio‡
		Mean (SD) = 5.19 (1.94)	Mean (SD) = 0.19 (0.11)	Mean (SD) = 4.95 (0.64)
Lowest 10%	35	0.21 (-0.50, 0.91)	-0.01 (-0.05, 0.03)	0.10 (-0.13, 0.33)
Upper 90%	332	0.00 (Reference)	0.00 (Reference)	0.00 (Reference)
P-value		0.56	0.75	0.39

^†Models include SES indicator of interest, maternal age at enrollment, race/ethnicity and smoking habits during pregnancy; child’s sex and age at the time of DNA methylation assessment (at birth, this variable was gestational age at delivery); and cell type distribution.

^‡%5mC:%5hmC is Log₂ transformed to meet normality assumptions.

^§Based on a weighted index comprising maternal self-reported household income, receipt of public assistance, education level, marital status, median household income (census tract), % of neighborhood below poverty line (census tract).

SD: Standard deviation; SES: Socioeconomic status.