A recent trial found that antenatal cholecalciferol supplementation has a protective effect on the risk of infantile atopic eczema through increased breast milk secretions of cholecalciferol. The trial results were published in the British Journal of Dermatology.
Atopic eczema is a chronic inflammatory health condition that originates in utero. Maternal vitamin D supplementation during pregnancy increased vitamin D activity in breast milk. As there is uncertainty if prenatal maternal vitamin D supplementation is associated with the offspring's risk of atopic eczema, researchers conducted a double-blind, randomized placebo-controlled trial to examine the influence of maternal cholecalciferol supplementation during pregnancy on the risk of atopic eczema in the offspring at ages 12, 24 and 48 months.

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Using data from the UK Maternal Vitamin D Osteoporosis Study (MAVIDOS) pregnant women were randomly allocated to either cholecalciferol 1000 IU per day or matched placebo, taken from around 14 weeks gestation until delivery. the primary outcome was the neonatal whole-body bone mineral content. based on the UK Working Party criteria for the definition of atopic dermatitis, the prevalence of atopic eczema in the offspring was ascertained at ages 12 (n = 635), 24 (n = 610), and 48 (n = 449) months. There were 635 infants at 12 months of age, 610 infants at 24 months of age, and 449 infants at 48 months of age.
Results:
Apart from longer breastfeeding duration in the intervention group, the characteristics of mothers and offspring were similar between the intervention and placebo groups.
Offspring of mothers who received cholecalciferol 1000 IU daily had a lower odds ratio (OR) of atopic eczema at age 12 months when adjusted for breastfeeding duration, but not statistically significant at ages 24 months or 48 months.
There was no significant statistical interaction of intervention and breastfeeding duration about eczema at age 12 months but reduced infantile eczema risk was seen through stratification in the intervention group for infants breastfed for ≥ 1 month and not in those that breastfed for < 1 month.
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This trial was the first randomized trial to find the protective effect of antenatal cholecalciferol supplementation on the risk of infantile atopic eczema through increased breast milk cholecalciferol levels. These results show a potentially modifiable perinatal influence on atopic eczema.
Further reading: El-Heis S, D'Angelo S, Curtis EM, et al. Maternal antenatal vitamin D supplementation and offspring risk of atopic eczema in the first 4 years of life: evidence from a randomized controlled trial. Br J Dermatol. 2022;187(5):659-666. doi:10.1111/bjd.21721