Association between maternal cholecalciferol supplementation and
offspring atopic eczema
The prevalences of atopic eczema in the intervention group at ages 12,
24 and 48 months were 7.2%, 11.4% and 6.7% respectively, compared
with 12.0%, 14.5% and 8.8% in the placebo group. Table 2 shows the OR
of atopic eczema at ages 12, 24 and 48 months in offspring whose mothers
received 1000IU cholecalciferol vs placebo. In an unadjusted analysis,
offspring of mothers who received 1000IU cholecalciferol had a lower
risk OR of atopic eczema at age 12 months, 0.57 (95%CI 0.33, 0.98), p =
0.04 compared to offspring of mothers who received placebo; this changed
little after adjusting for breastfeeding duration as a covariate. The
ORs of atopic eczema in the intervention group compared to the control
group at ages 24 and 48 months were 0.75 (0.47, 1.21) p = 0.25, and 0.75
(0.37, 1.50) p = 0.41, respectively, and changed little in models
adjusted for breastfeeding (Table 2) or season at birth. Adjusted
estimates are presented graphically in Figure 1. Sensitivity analysis
stratified by breastfeeding duration demonstrated a reduced risk of
atopic eczema at age 12 months in the intervention group in infants who
were breastfed for more than one month (OR 0.48 (0.24,0.94), p = 0.03),
but not in those who were breastfed for less than one month (OR 0.80
(0.29,2.17), p = 0.66) (Table 3); however, interaction terms between the
intervention and breastfeeding duration were not statistically
significant at any of the three follow-up ages (p = 0.41, 0.35, 0.13 at
ages 12, 24 and 48 months, respectively).
Sensitivity analyses showed no association between maternal late
pregnancy serum 25(OH)D and offspring atopic eczema at any age
(Supplementary table 3). Examining the SNPs rs12785878 (DHCR7 ),
rs10741657 (CYP2R1 ) and rs6013897 (CYP24A1 ) located in
genes involved in vitamin D metabolism10, 14,
demonstrated no associations with offspring atopic eczema, although
there indications of higher ORs for atopic eczema with rs10741657
(CYP2R1 ) at ages 12 and 24 months, OR 1.44 (0.95, 2.18), p =
0.08, and 1.42 (0.98, 2.04), p = 0.06, respectively (Table 4).