Vitamin C Supplementation Among Pregnant Smokers and Airway Function Trajectory in Offspring: A Secondary Analysis of a Randomized Clinical Trial.

This secondary analysis of a randomized clinical trial analyzes the association of vitamin C supplementation in women who smoked during pregnancy with airway function trajectory in their offspring at 4 to 6 years of age.

Effect of Vitamin C Supplementation for Pregnant Smokers on Offspring Airway Function and Wheeze at Age 5 Years: Follow-up of a Randomized Clinical Trial.

Importance: Vitamin C supplementation (500 mg/d) for pregnant smokers has been reported to increase offspring airway function as measured by forced expiratory flow (FEF) through age 12 months; however, its effects on airway function at age 5 years remain to be assessed. Objective: To assess whether vitamin C supplementation in pregnant smokers is associated with increased and/or improved airway function in their offspring at age 5 years and whether vitamin C decreases the occurrence of wheeze. Design, Setting, and Participants: This study followed up the Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) double-blind, placebo-controlled randomized clinical trial conducted at 3 centers in the US (in Oregon, Washington, and Indiana) between 2012 and 2016. Investigators and participants remain unaware of the treatment assignments. Forced expiratory flow measurements at age 5 years were completed from 2018 to 2021. Interventions: Pregnant smokers were randomized to vitamin C (500 mg/d) or placebo treatment. Main Outcomes and Measures: The primary outcome was the prespecified measurement of FEF between 25% and 75% expired volume (FEF25-75) by spirometry at age 5 years. Secondary outcomes included FEF measurements at 50% and 75% of expiration (FEF50 and FEF75), forced expiratory volume in 1 second (FEV1), and occurrence of wheeze. Results: Of the 251 pregnant smokers included in this study, 125 (49.8%) were randomized to vitamin C and 126 (50.2%) were randomized to placebo. Of 213 children from the VCSIP trial who were reconsented into this follow-up study, 192 (90.1%) had successful FEF measurements at age 5 years; 212 (99.5%) were included in the analysis of wheeze. Analysis of covariance demonstrated that offspring of pregnant smokers allocated to vitamin C compared with placebo had 17.2% significantly higher mean (SE) measurements of FEF25-75 at age 5 years (1.45 [0.04] vs 1.24 [0.04] L/s; adjusted mean difference, 0.21 [95% CI, 0.13-0.30]; P < .001). Mean (SE) measurements were also significantly increased by 14.1% for FEF50 (1.59 [0.04] vs 1.39 [0.04] L/s; adjusted mean difference, 0.20 [95% CI, 0.11-0.30]; P < .001), 25.9% for FEF75 (0.79 [0.02] vs 0.63 [0.02] L/s; 0.16 [95% CI, 0.11-0.22]; P < .001), and 4.4% for FEV1 (1.13 [0.02] vs 1.09 [0.02] L; 0.05 [95% CI, 0.01-0.09]; P = .02). In addition, offspring of pregnant smokers randomized to vitamin C had significantly decreased wheeze (28.3% vs 47.2%; estimated odds ratio, 0.41 [95% CI, 0.23-0.74]; P = .003). Conclusions and Relevance: In this follow-up study of offspring of pregnant smokers randomized to vitamin C vs placebo, vitamin C supplementation during pregnancy resulted in significantly increased airway function of offspring at age 5 years and significantly decreased the occurrence of wheeze. These findings suggest that vitamin C supplementation for pregnant smokers may decrease the effects of smoking in pregnancy on childhood airway function and respiratory health. Trial Registration: ClinicalTrials.gov Identifier: NCT03203603.

Cost effectiveness of vitamin c supplementation for pregnant smokers to improve offspring lung function at birth and reduce childhood wheeze/asthma.

OBJECTIVE: To determine the implications of supplemental vitamin C for pregnant tobacco smokers and its effects on the prevalence of pediatric asthma, asthma-related mortality, and associated costs. STUDY DESIGN: A decision-analytic model built via TreeAge compared the outcome of asthma in a theoretical annual cohort of 480,000 children born to pregnant smokers through 18 years of life. Vitamin C supplementation (500 mg/day) with a standard prenatal vitamin was compared to a prenatal vitamin (60 mg/day). Model inputs were derived from the literature. Deterministic and probabilistic sensitivity analyses assessed the impact of assumptions. RESULT: Additional vitamin C during pregnancy would prevent 1637 cases of asthma at the age of 18 per birth cohort of pregnant smokers. Vitamin C would reduce asthma-related childhood deaths and save $31,420,800 in societal costs over 18 years per birth cohort. CONCLUSION: Vitamin C supplementation in pregnant smokers is a safe and inexpensive intervention that may reduce the economic burden of pediatric asthma.