ATS 2012, SAN FRANCISCO -Vitamin C supplementation in pregnant women who are unable to quit smoking significantly improves pulmonary function in their newborns, according to a new study.
"Smoking during pregnancy is known to adversely affect the lung development of the developing baby," said Cindy McEvoy, MD, associate professor of pediatrics at Oregon Health & Science University Doernbecher Children's Hospital. "We found that daily use of vitamin C (500 mg/day) by smoking pregnant woman significantly improved pulmonary function tests administered to their offspring at about 48 hours postpartum."
The results will be presented at the ATS 2012 International Conference in San Francisco.
The study enrolled the newborns of 159 smoking women and randomized them to daily vitamin C (500 mg) or placebo before 22 weeks gestation and treatment was continued through delivery.76 non smoking pregnant women were also studied. The primary outcome of the study was the measurement of the newborn's lung function with a pulmonary function test at about 48 hours of life. This assessment included measurement of peak tidal expiratory flow to expiratory time (TPTEF:TE) and respiratory compliance (Crs).
Smokers treated with placebo had significantly lower levels of ascorbic acid than non-smokers, but levels returned to those of non-smokers in smokers randomized to vitamin C. Newborns of smoking women randomized to placebo had decreased TPTEF:TE and Crs compared to non-smokers. Both TPTEF:TE and Crs were significantly increased by vitamin C supplementation, returning them nearly to the levels seen in non-smokers.
"In our pilot study, we were able to show that babies born to smoking pregnant women who were randomized to daily supplemental vitamin C had significantly improved pulmonary/lung function tests compared to babies born to smoking women who were randomized to placebo," said Dr. McEvoy.
"Moreover, although our study numbers were small, we found that one particular genetic variant that has been shown to increase the risk of smokers developing cancer and is associated with both a reduced ability to quit smoking and a high likelihood of relapse, also seemed to intensify the harmful effects of maternal smoking on babies' lungs. Although the lung function of all babies born to smokers in our study was improved by supplemental vitamin C, our preliminary data suggest, importantly, that vitamin C may help those babies at the greatest risk of harm during their development from their mother's smoking in pregnancy."
"Getting women to quit smoking during pregnancy has to be priority one, but this study provides a way to potentially help the infants born to at least 12% of pregnant women who cannot quit smoking when pregnant." said Dr. McEvoy. "Vitamin C supplementation may block some of the in-utero effects of smoking on fetal lung development."
"Our findings are important because improved lung function tests at birth are associated with less wheezing and asthma in childhood," concluded Dr. McEvoy. "Vitamin C is a simple, safe, and inexpensive treatment that may decrease the impact of smoking during pregnancy on the respiratory health of children."
"Daily Vitamin C Improves Pulmonary Function In Newborns Of Pregnant Smoking Women: A Randomized Trial" (Session C16, Tuesday, May 22, 8:45 a.m., Room 2006-2008, Moscone Center; Abstract 25842)
* Please note that numbers in this release may differ slightly from those in the abstract. Many of these investigations are ongoing; the release represents the most up-to-date data available at press time.
Daily Vitamin C Improves Pulmonary Function In Newborns Of Pregnant Smoking Women: A Randomized Trial
Type: Scientific Abstract
Category: 14.01 - Neonatal Lung Disease and BPD (PEDS)
Authors: C. McEvoy1, D. Schilling1, N. Clay1, M. Go1, P. Spitale1, C. Bunten2, M. Leiva3, J. Hollister-Smith1, M. Durand4, B. Frei5, A.S. Buist1, D. Peters1, C. Morris1, E. Spindel1; 1Oregon Health & Science University - Portland, OR/US, 2Vancouver Clinic - Vancouver, WA/US, 3Providence Portland Medical Center - Portland, OR/US, 4University of Southern California - Los Angeles, CA/US, 5Oregon State University - Corvallis, OR/US
RATIONALE: Maternal smoking during pregnancy adversely affects lung development with lifelong decreases in pulmonary function and increased risk of asthma. In a non-human primate model, supplemental vitamin C blocked the in-utero effects of nicotine on fetal lung development and offspring pulmonary function (Am J Respir Crit Care Med 2005; 171:1032-39). We hypothesized that newborns of smoking pregnant women randomized to daily vitamin C would have improved pulmonary function tests (PFTs) compared to those randomized to placebo.
METHODS: Pregnant women unable to quit smoking were randomized to daily vitamin C (500 mg) versus placebo prior to 22 weeks gestation through delivery. Urine cotinine and fasting plasma ascorbic acid were measured. A group of non smoking pregnant women was also studied (reference group). The primary outcome was the measurement of PFTs in the newborns at about 48 hours of age. Flow volume characteristics including the time to peak tidal expiratory flow to expiratory time (TPTEF:TE) and passive respiratory mechanics (respiratory compliance [Crs]) were measured (Viassys Jaeger BabyBody). Analysis of the primary outcomes was done on intention-to-treat using linear regression and adjusting for stratification for randomization (<16 versus ≥ 16 weeks' gestation).
RESULTS: 159 newborns of randomized smoking women and 76 of non smoking women were studied. There were no significant differences between randomized groups with regards to maternal age, insurance coverage, cotinine levels, women smoking ≥ 10 cigarettes daily, medication adherence, or history of asthma. The smoking women randomized to placebo had significantly lower levels of ascorbic acid than non-smokers, but vitamin C returned levels to that of non-smokers . There was no significant difference between randomized groups in gestational age at randomization, delivery mode, and gestational age at birth, birth weight, race or gender. Newborns of smoking women randomized to placebo had decreased TPTEF:TE and Crs compared to non-smokers, but vitamin C supplementation significantly increased TPTEF:TE and Crs, returning them nearly to levels of non-smokers.
CONCLUSION: Newborns delivered to smoking women randomized to vitamin C had significantly improved PFTs (increased TPTEF:TE and Crs) compared to those randomized to placebo. Assessment of clinical outcomes through one year of age is ongoing. We speculate that vitamin C supplementation in pregnant women who cannot quit smoking has great public health significance to potentially alter the fetal origins of respiratory disease by blocking some of the effects of in-utero smoke on lung development.
Funded by: NIH/ NHLBI