Maternal smoking during pregnancy is known to have detrimental effects on offspring respiratory health, including an increased risk of wheeze. A recent secondary analysis of clinical trial data investigated the association between vitamin C supplementation during pregnancy and wheeze occurrence in children exposed to maternal smoking. This study was published in the JAMA Pediatrics journal. The study was conducted by McEvoy C. T. and colleagues.

Children exposed to maternal smoking during pregnancy face an elevated risk of respiratory issues, including wheeze, later in life. Vitamin C supplementation has shown promise in mitigating some of these adverse effects, possibly by improving airway function. However, the specific mechanisms underlying this association remain unclear.
Researchers conducted a longitudinal analysis of data from the Vitamin C to Decrease Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) trial, which randomized pregnant women who smoked to receive either vitamin C or placebo. Children's forced expiratory flow measurements and wheeze occurrences were assessed at ages 3, 12, and 60 months.
The key findings of the study were as follows:
• Children whose mothers received vitamin C supplementation during pregnancy exhibited significantly higher forced expiratory flow values compared to those whose mothers received placebo.
• Wheeze occurrence was significantly lower in children whose mothers received vitamin C supplementation, particularly between ages 4 and 6 years.
• Approximately 54.2% of the association between vitamin C supplementation and reduced wheeze was mediated through improved forced expiratory flow.

• Maternal smoking during pregnancy was directly associated with wheeze occurrence in offspring.
The study provides evidence supporting the beneficial effects of vitamin C supplementation during pregnancy on children's respiratory health, particularly in the context of maternal smoking. Improved airway function mediated the association between vitamin C supplementation and reduced wheeze, highlighting a potential mechanism of action.
Vitamin C supplementation during pregnancy may offer protective effects against wheeze in offspring exposed to maternal smoking. These findings underscore the importance of prenatal interventions in mitigating the adverse respiratory effects of maternal smoking and the potential role of vitamin C supplementation in improving children's respiratory outcomes. Further research is warranted to elucidate the long-term effects and mechanisms of action of vitamin C supplementation on respiratory health in children.
Reference:
McEvoy, C. T., Shorey-Kendrick, L. E., MacDonald, K. D., Park, B. S., Spindel, E. R., Morris, C. D., & Tepper, R. S. (2024). Vitamin C supplementation among pregnant smokers and airway function trajectory in offspring: A secondary analysis of a randomized clinical trial. JAMA Pediatrics. https://doi.org/10.1001/jamapediatrics.2024.0430