Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP). A Randomized Trial
What this study found
Vitamin C did not significantly improve the primary outcome of infant FEF75 at 3 months, but it did improve several secondary airway function measures. For FEF75, adjusted mean difference was 16.2 (-3.3, 35.6), p=0.10; for FEF50, adjusted mean difference was 33.7 (6.1, 61.3), p=0.02; for FEF25-75, adjusted mean difference was 28.1 (0.9, 55.3), p=0.04; and for FEV0.5, adjusted mean difference was 8.6 (0.7, 16.4), p=0.03. The authors concluded that prenatal vitamin C may be a safe, inexpensive way to modestly improve infant airway function when smoking cessation is not achieved. No serious…
- Study & population
- Randomized, placebo-controlled trial at 3 sites in pregnant, English-speaking smokers with singleton gestations enrolled between 13 0/7 and 22 6/7 weeks.
- Intervention
- Pregnant smokers were randomized to oral vitamin C 500 mg/day as an ascorbic acid capsule taken once daily until delivery, or matching placebo.
- Key limitation
- The primary endpoint was not statistically significant, and the observed benefits were modest and concentrated in secondary outcomes.
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Open PDFOriginal abstract
Rationale: We reported a randomized trial demonstrating daily supplemental vitamin C to pregnant smokers significantly improved newborn pulmonary function tests. The current study tests these results in a new cohort using infant pulmonary function tests. Objectives: To determine if infants of pregnant smokers randomized to daily supplemental vitamin C would have improved forced expiratory flows (FEFs) at 3 months of age compared with those randomized to placebo, and to investigate the association of the &agr;5 nicotinic acetylcholine receptor. Methods: A randomized, double‐blind, placebo‐controlled trial was conducted at three centers. Two hundred fifty‐one pregnant smokers were randomized at 13‐23 weeks of gestation: 125 randomized to vitamin C (500 mg/d) and 126 to placebo. Measurements and Main Results: The primary outcome was FEF75 at 3 months of age performed with the raised volume rapid thoracic compression technique (Jaeger/Viasys). FEF50 and FEF25‐75 obtained from the same expiratory curves were prespecified secondary outcomes. The infants of pregnant smokers randomized to vitamin C (n = 113) had the following FEFs at 3 months of age compared with those randomized to placebo (n = 109) as measured by FEF75 (200.7 vs. 188.7 ml/s; adjusted 95% confidence interval [CI] for difference, ‐3.33 to 35.64; P = 0.10), FEF50 (436.7 vs. 408.5 ml/s; adjusted 95% CI for difference, 6.10‐61.30; P = 0.02), and FEF25‐75 (387.4 vs. 365.8 ml/s; adjusted 95% CI for difference, 0.92‐55.34; P = 0.04). Infant FEFs seemed to be negatively associated with the maternal risk alleles for the &agr;5 nicotinic acetylcholine receptor (rs16969968). Conclusions: Although the primary outcome of FEF75 was not improved after vitamin C supplementation to pregnant smokers, the predetermined secondary outcomes FEF50 and FEF25‐75 were significantly improved. These results extend our previous findings and demonstrate improved airway function (FEF50 and FEF25‐75) at 3 months of age in infants after vitamin C supplementation to pregnant smokers. Clinical trial registered with www.clinicaltrials.gov (NCT 01723696).