Associations of maternal vitamin D intake during pregnancy with asthma and other allergies in Japanese infants

Vitamin D is known to have an immunological effect and may play an important role in allergic diseases. We investigated the associations of maternal intake of vitamin D during pregnancy with the risks of allergies in infants. Subjects were from a birth cohort constructed prenatally. Maternal intake of vitamin D during pregnancy was evaluated using a 5-day dietary record. After birth, 312 children were followed for physician-diagnosed allergic diseases until the ages of approximately 3 and 5 years old. As compared with the lowest, the highest maternal vitamin D intake from diet plus supplements during pregnancy was significantly associated with a reduced risk of physician-diagnosed asthma in children younger than 3 years of age after controlling for potential confounders. Statistically significant trends were also observed (p=0.006). Relative to the lowest, the highest maternal vitamin D intake was associated with an increased risk of eczema in children under 3 years old. The results of this study suggest that the maternal intake of vitamin D during pregnancy is inversely associated with asthma and positively associated with atopic eczema in infants.