One positive:
Vitamin C Supplementation for Pregnant Smoking Women and Pulmonary Function in Their Newborn Infants: A Randomized Clinical Trial (PDF)
One negative
Effect of Vitamin D3 on Asthma Treatment Failures in Adults With Symptomatic Asthma and Lower Vitamin D Levels. The VIDA Randomized Clinical Trial (PDF)
Pregnant women and people with AIDS seem to be two population where vitamins and supplements have a better track record. Everywhere else is just a wasteland of negative trials.