Updated results on a study of vitamin D and childhood asthma has found extra supplements in pregnancy fails to reduce the risk of asthma or wheezing in children.

By age six, 43.5% of the children, whose mothers had received the extra vitamin D, had asthma or recurrent wheezing, compared with 45.9% in the control group.

The difference was not significant, Dr Augusto Litonjua, of Golisano Children’s Hospital in Rochester, New York, US, and colleagues reported in the New England Journal of Medicine.

Nor did the risk of asthma or wheezing correlate with maternal 25-hydroxyvitamin D levels during pregnancy.