Vitamin D in pregnancy reduces wheezing

High levels of vitamin D, obtained through diet or supplements, during pregnancy appears to reduce the risk of recurrent wheezing or wheezing symptoms in early childhood. Researchers from the Massachusetts General Hospital in Boston, USA, used a food questionnaire to assess vitamin D levels during pregnancy and then correlated these findings with recurrent wheeze in the child at 3 years of age. A total of 1,194 mother-child pairs were included in the analysis. The average total vitamin D level during pregnancy was 548 IU per day. Recurrent wheeze was identified in 186 children. Mothers in the top 25 percent of vitamin D were 61-percent less likely to have a child with recurrent wheeze compared with those in the lowest 25 percent. For each 100-IU increase in vitamin D, the risk of having a child with recurrent wheeze fell by 19 percent. This benefit was noted whether the vitamin D came from supplements or the diet. In another study, researchers from the Channing Laboratory in Boston, USA, examined the impact of maternal vitamin D intake on childhood wheezing symptoms at 5 years of age. This study involved 1212 mother-child pairs. Compared with the group with the lowest vitamin D levels, women with the highest levels of vitamin D had a 52-percent reduced risk of wheeze and a 65-percent reduced risk of wheeze in the previous year in their children. The results of these two studies are of great public health significance because they could lead to relatively low cost interventions of vitamin D supplementation that would have a large effect on the future prevalence of asthma in children.