China: A recent study published in The Journal of Nutritional Biochemistry has shown that low levels of prenatal maternal vitamin D increase the risk of infantile eczema aged 0–1 year. In the study, 63.9% of pregnant mothers exhibited insufficient or deficient levels of 25(OH)D3.
This may be related to the downregulation of the FOXP3 gene expression in cord blood and reduced placental FOXP3 protein expression. Low placental FOXP3 protein was related to activating the PI3K/AKT/mTOR signalling pathway.

Eczema is a kind of skin hypersensitivity that commonly initiates in early childhood, typically at age 3-6 months. In infants, eczema is frequently the first demonstration of atopic disorder to appear, and it can develop into other atopic diseases such as asthma, food allergy, and allergic rhinitis. A substantial proportion of children are affected by eczema, with a global report of 13.5% to 41.9%. Despite increasing research on eczema, there has been no clarity on its aetiology in recent years. However, it has been known that eczema development may be influenced by the interaction of environmental and genetic factors.
Vitamin D has received increasing attention owing to its association with the development of atopic disease. There is still an ongoing debate on the limited studies that have been done on the impact of maternal vitamin D levels during pregnancy on infantile eczema. Ya-Jie Ding, Huizhou Institute for Occupational Health, Huizhou, China, and colleagues wanted to discover the effect of maternal vitamin D on infantile eczema and explore the role of regulatory T cells (Treg) in this process.
For this purpose, the researchers enrolled 219 pairs of mothers and children. To determine vitamin D levels, maternal fasting venous blood was collected in the second and third trimesters of the pregnancy. Cord blood and placenta samples were collected during childbirth to detect levels of proteins, genes, and cytokines. Paediatricians followed up on the prevalence of eczema in infants within 1 year.
The study led to the following findings:
The reported rate of vitamin D deficiency and insufficiency was 35.6% and 28.3%.
Lower maternal 25(OH)D3 levels were related to a higher risk of infantile eczema.
Foxp3 gene expression is lower in the cord blood of infants with eczema compared to infants without eczema.
There was a positive correlation between maternal 25(OH)D3 levels and the expression of the FOXP3 gene in cord blood.
Compared to vitamin D sufficiency women, vitamin D deficiency women's placental FOXP3 protein expression was decreased and PI3K/AKT/mTOR protein was up-regulated.
"Vitamin D deficiency in women during pregnancy raises the risk of infantile eczema by mechanisms associated with down-regulation of the FOXP3 gene in umbilical cord and reduced placental FOXP3 protein expression," the researchers concluded.
Reference:
Ding, Y., Li, X., Xiao, Z., Li, C., & Jia, L. (2023). Low vitamin D during pregnancy is associated with infantile eczema by up-regulation of PI3K/AKT/mTOR signaling pathway and affecting FOXP3 expression: A bidirectional cohort study. The Journal of Nutritional Biochemistry, 109516. https://doi.org/10.1016/j.jnutbio.2023.109516