Does vitamin C in pregnant smokers improve the trajectory of airway function in the offspring? | Image credit: © New Africa – © New Africa -stock.adobe.com.
Important points:
- In a secondary analysis of the VCISP trial, offspring of pregnant smokers who received vitamin C supplementation had significantly higher forced expiratory flow (FEF25-75) by age 5 compared to children who received a placebo. It was shown that
- The vitamin C group also showed a lower incidence of wheezing at ages 4 to 6 years compared to the placebo group.
- Mediation analysis suggested that most of the association between vitamin C and reduced wheezing incidence was mediated by improved FEF25-75.
Investigators in recent research letters published in JAMA Pediatrics To better understand how vitamin C supplementation of pregnant smokers affects the trajectory of airway function in their offspring, we highlighted a secondary analysis of a randomized clinical trial.1
The original study, the Vitamin C to Reduce the Effects of Smoking During Pregnancy on Infant Lung Function (VCISP) trial, found that supplementing women who smoked during pregnancy with vitamin C at 3 and 12 months of age The child’s forced expiratory flow (FEF) increased “significantly.” of age.1
The study was randomized, double-blind, and placebo-controlled and was conducted at three centers in 251 pregnant smokers who were randomized between 13 and 23 weeks of pregnancy. Of these participants, 125 were randomized to vitamin C (500 mg/day) and 126 to placebo.2, 3
The primary outcome was FEF75 (Measurement of FEF at 75% of exhaled volume) 3rd month.Although this result was not met, the FEF side result was50 and FEF25-75 Significant improvement occurred at 3 and 12 months of age.2, 3
The researchers demonstrated that FEF continued to be significantly higher in the offspring over a 60-month long-term follow-up.25-75 The occurrence of wheezing is significantly reduced.1
To assess the relevance of FEF25-75 Because of the onset of wheezing between ages 4 and 6, the study authors conducted a new longitudinal analysis of FEF.25-75 Data from the VCSIP trial and new mediation analysis from offspring of women who smoked during pregnancy at 3, 12, and 60 months of age.1
FEF was measured using spirometry at 3, 12, and 60 months of age, and wheezing was measured by quarterly standardized respiratory questionnaires. Long-term treatment differences in FEF25-75 A general linear mixed model was assessed by repeated measures of covariance.1
Results show that 243 offspring were born, 233 had 1 of 3 FEF measurements, and 80% had data at 60 months and 80% had data at 3 or 12 months. I had.1
Longitudinal FEF25-75 Analysis revealed that “vitamin C group (P < .001), FEF increases significantly by 25% to 75% with increasing age," the researchers said.1 The incidence of wheezing was significantly lower in the vitamin C group (30 vs. 50) [28.3% vs 47.2%]odds ratio: 0.41, 95% CI, 0.23-0.74 [P = .003]).1
Furthermore, mediation analysis revealed that most of the association between vitamin C and wheezing was mediated through the association between vitamin C and increased FEF.25-75 (Total percentage 54.2% [P = .03]).1
Secondary analysis revealed that vitamin C supplementation in women who smoked during pregnancy led to an increase in FEF25-75 Trajectory of offspring up to age 5. Differences in FEF25-75 Mean values among treatment groups increased with age, despite not receiving postnatal supplements, the researchers wrote.1
In addition, the vitamin C group had less incidence of wheezing at ages 4 to 6 years.
“Our findings provide evidence that there is a direct association between maternal smoking during pregnancy and the occurrence of wheezing in children,” the authors concluded.
References:
1. McEvoy CT, Shorey-Kendrick LE, MacDonald KD, et al. Vitamin C supplementation in pregnant smokers and the trajectory of offspring airway function: a secondary analysis of a randomized clinical trial. JAMA Pediatrics. Published online on April 8, 2024. doi:10.1001/jamapediatrics.2024.0430
2. McEvoy CT, Shorey-Kendrick LE, Milner K, et al. Oral vitamin C (500 mg/day) to smokers during pregnancy improves airway function in infants at 3 months of age (VCSIP). Randomized trial. Am J Respir Crit Care Med. 2019;199(9):1139-1147. doi:10.1164/rccm.201805-1011OC
3. McEvoy CT, Shorey-Kendrick LE, Milner K, et al. Vitamin C administration to pregnant smokers results in sustained improvements in airway function in infants up to 12 months of age: a randomized trial. European Respiratory Journal. December 2020, 56(6)1902208; DOI: 10.1183/13993003.02208-2019
