Association between vitamin D status in early pregnancy and atopy in offspring in a vitamin D deplete cohort

Background: Vitamin D status may play a role in the development of atopic diseases due to its action on lung development and immune system development and function. Aims: Our objective was to assess whether 25-hydroxyvitamin D (25OHD) levels in maternal blood in pregnancy were associated with atopy in children. Methods: We analysed 279 mother-child pairs from the ROLO study conducted in Dublin, Ireland. Serum 25OHD was measured at 13 and 28 weeks of pregnancy. Development of childhood atopy was self-reported by mothers at follow-up appointments at 6 months, 2 years or 5 years. Logistic regression analysis was used to evaluate associations between maternal 25OHD status and development of atopy. Results: The mean (SD) 25OHD levels in early and late pregnancy were 41.9 (19.2) nmol/L and 40.2 (21.6) nmol/L, respectively. Maternal 25OHD status in early pregnancy, but not in late pregnancy, was associated with a reduced risk of atopy at 2 years (OR 0.972, CI 0.946–0.999). In early pregnancy, those with serum 25OHD levels < 30 nmol/L compared with those with 25OHD > 50 nmol/L had significantly greater risk of developing atopy at 2 years (OR 4.76, CI 1.38–16.47). Conclusions: The development of childhood atopy may be associated with maternal vitamin D deficiency in early pregnancy among a cohort of women at risk of vitamin D deficiency. Further research is required to explore the relationship between vitamin D and atopy, particularly among women with poor vitamin D status, and whether supplementation should be prioritised in early pregnancy to reduce childhood atopy.