Cindy T. McEvoy, MD, from the Oregon Health & Science University, in Portland, and colleagues examined the impact of supplemental daily vitamin C during pregnancy on the incidence of wheezing within the first year of life. The infants of 76 smokers randomized to vitamin C, the infants of 83 smokers randomized to placebo, and the infants of 76 nonsmokers were assessed at delivery. Ninety-two percent were followed through age 1.
The researchers found that significantly fewer infants of vitamin-C treated versus placebo-treated smokers had at least one episode of wheezing (21 versus 40 percent; adjusted P = 0.019) and fewer infants received medication for wheezing (13 versus 22 percent; adjusted P = 0.14). The incidence of wheezing was significantly lower for those randomized to vitamin C versus placebo for infants of pregnant smokers homozygous or heterozygous for the rs16969968 risk allele (14 versus 48 percent; P = 0.01).
"Vitamin C is a simple, safe, and inexpensive treatment that may decrease the impact of smoking during pregnancy on childhood respiratory health," McEvoy said in a statement. "Though the lung function of all babies born to smokers in our study was improved by supplemental vitamin C, our preliminary data suggest that vitamin C appeared to help those babies at the greatest risk of harm during their development from their mother's smoking in pregnancy."