Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP) A Randomized Trial
Supported by the NHLBI (R01 HL105447 and R01 HL105460) with cofunding from the Office of Dietary Supplements and by P51OD011092 and UG3 OD023288. Additional support from the Oregon Clinical Translational Research Institute funded by the National Center for Advancing Translational Sciences (UL1TR000128).
American Journal of Respiratory and Critical Care Medicine
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 α5 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 α5 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 (FEF50and FEF25–75) at 3 months of age in infants after vitamin C supplementation to pregnant smokers.
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McEvoy, C. T., Shorey-Kendrick, L. E., Milner, K., Schilling, D., Tiller, C., Vuylsteke, B., … Morris, C. D. (2019). Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP). A Randomized Trial. American Journal Of Respiratory And Critical Care Medicine, 199(9), 1139–1147. https://doi.org/10.1164/rccm.201805-1011OC
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