Fetuses of Pregnant Smokers Benefit From Vitamin C

Pregnant women who are unable or unwilling to quit smoking can help improve lung function in their newborns by taking 500 mg of vitamin C daily, according to results of a new pilot study presented at the American Thoracic Society 2012 International Conference in May.¹

Smoking during pregnancy is well known to adversely affect lung development and function in the children of women who smoke and is associated with lifelong decreases in pulmonary function and increases in risk of asthma. Previous research in primates has shown that vitamin C inhibited the effects of in utero nicotine exposure on fetal lung development and on lung function in offspring.² 

In this new pilot study, pregnant women were randomized to receive either 500 mg of daily vitamin C or placebo before 22 weeks of gestation through delivery.¹ A group of nonsmoking pregnant women were studied as a reference group. Urine cotinine and fasting plasma ascorbic acid levels were measured for all participants.

A total of 159 newborns of smoking women and 76 newborns of nonsmoking women were studied. The pulmonary function of all newborns was measured at around 48 hours after birth using standard newborn pulmonary function testing-time to peak tidal expiratory flow to expiratory time and passive respiratory mechanics (respiratory compliance). Researchers found that the newborns of women who smoked and took vitamin C had significantly better lung function than the newborns of women who smoked and took placebo.¹ In addition, researchers determined that the presence of a genetic variant that is associated with a reduced ability to quit smoking and an increased likelihood of relapse that can also increase the risk of cancer in persons who smoke seems to intensify the harmful effects of maternal smoking on infants’ lungs.

“Our findings our important because improved lung function tests at birth are associated with less wheezing and asthma in childhood,” said study author Cindy McEvoy, MD, MCR. “Vitamin C is a simple, safe, and inexpensive treatment that may decrease the impact of smoking during pregnancy on the respiratory health of children.”

Pertinent Point:
- For pregnant women who are unable to quit smoking, a daily dose of 500 mg of vitamin C may alter the fetal origins of respiratory disease by blocking some of the negative effects of smoking on fetal lung development.

References:

1. McEvoy C, Schilling D, Clay N, et al. Daily vitamin C improves pulmonary function in newborns of pregnant smoking women: a randomized trial. In: Program and abstracts of the American Thoracic Society 2012 International Conference; May 18-23, 2012; San Francisco. Abstract 25842. Available at: http://www.ohsu.edu/xd/about/news_events/news/2012/05-22-vitamin-C-improves-lung.cfm. Accessed June 19, 2012.
2. Proskocil BJ, Sekhon HS, Clark JA, et al. Vitamin C prevents the effects of prenatal nicotine on pulmonary function in newborn monkeys. Am J Respir Crit Care Med. 2005;171:1032-1039.