Vitamin C Supplementation for Pregnant Smoking Women and Pulmonary Function in Their Newborn Infants: A Randomized Clinical Trial

摘要

Offspring of smokers who continue to smoke during pregnancy show adverse effects in their lung development, with lifelong decreases in pulmonary function. Clinical trials of smoking cessation during pregnancy have been ineffective. This randomized, double-blind, placebo-controlled study was performed to determine whether vitamin C supplementation decreases the effects of maternal smoking on newborn pulmonary function test (PFT) results. Pregnant smokers received either vitamin C (500 mg/d) or placebo; pregnant nonsmokers constituted a reference group. Parturients were 15 years or older, were current smokers, had a singleton gestation, and had declined smoking cessation. The smokers took 1 crushed vitamin C (500 mg) or ground cornstarch (placebo) gel capsule daily until delivery and were supplied a standard prenatal vitamin containing 60 mg of vitamin C. The nonsmokers were not randomized to study medications but were given the standard prenatal vitamin. The primary outcome was the measurement of newborn PFTs (72 hours of age), specifically the ratio of time to peak tidal expiratory flow to expiratory time (TPTEF:TE) and passive respiratory system compliance (Crs) per kilogram. Secondary outcomes were the clinical respiratory outcomes of the infants until 1 year of age, including wheezing and use of medication for wheezing, and PFTs at 1 year.