Litonjua AA, Carey VJ, Laranjo N, et al. - This study was attempted to ascertain whether, when maternal levels of 25-hydroxyvitamin D were taken into account, children born to mothers who had received 4400 IU of vitamin D3 per day during pregnancy (vitamin D group) would have a lower incidence of asthma and recurrent wheeze at the age of 6 years than would those born to mothers who had received 400 IU of vitamin D3 per day (control group). Researchers applied time-to-event methods to compare the treatment groups with respect to time to the onset of asthma or recurrent wheeze. They applied multivariate methods to compare longitudinal measures of lung function between the treatment groups. The results showed that, among children who were at risk of asthma, vitamin D supplementation during the prenatal period alone did not affect the 6-year incidence of asthma and recurrent wheeze.