Early Pregnancy Vitamin D Status is Associated with Blood Pressure in Children: an Odense Child Cohort Study

Background: Blood pressure in childhood tracks into later life. Vitamin D status in adults is associated with blood pressure, but the impact of vitamin D status in pregnancy and childhood on blood pressure still needs investigation.

Objective: We investigated whether fetal rather than current vitamin D status is associated with blood pressure in children.

Methods: In a prospective observational study within the population-based Odense Child Cohort (OCC), we examined serum 25-hydroxyvitamin D2+3 [s-25(OH)D] in early and late pregnancy, cord blood, and at 5 y age, and the associations with systolic and diastolic blood pressure (SBP/DBP) in the 5-y-old children (n = 1,677). Multiple regression models were adjusted for maternal country of origin, parity, smoking during pregnancy, 5-y height, and weight. Two-stage mixed effect modeling was performed, integrating all s-25(OH)D data from pregnancy and cord blood.

Results: The median (IQR) s-25(OH)D in early pregnancy, late pregnancy, the umbilical cord, and at 5 y was 65.5 (50.7-78.5), 78.5 (60.3- 95.8), 45.4 (31.1- 60.7), and 71.9 (54.6- 86.5) nmol/L, respectively. The mean ±SD 5-y SBP/DBP was 101.0/63.8 (7.1/5.9) mmHg. In adjusted analyses, a 10 nmol/L increase of s-25(OH)D in early pregnancy associated with a 0.3/0.2 mmHg lower SBP/DBP at 5 y (P < 0.05). Optimal s-25(OH)D (>75 nmol/L) in early pregnancy was associated with lower 5-y SBP and DBP, β (95% CI) -1.45 (-2.6, -0.3), and -0.97 (-1.9, -0.1), compared with reference s-25(OH)D (50-74.9 nmol/L). Two-stage analysis combining early pregnancy, late pregnancy, and cord s-25(OH)D data showed an inverse association with 5-y SBP and DBP for boys (P < 0.025) with significant sex-difference for DBP (Pinteraction = 0.004). No associations were found between s-25(OH)D and 5-y BP above the 90th percentile.

Conclusion: Early pregnancy s-25(OH)D concentrations, especially >75 nmol/L, were inversely associated with 5-y blood pressure in the offspring. A novel identified protective effect of optimal vitamin D levels in early pregnancy on offspring BP is suggested.