Vitamin C and Pregnant Women Who Smoke

Improving pulmonary function in newborns.

500 mg of daily vitamin C given to pregnant smoking women “decreased the effects of in-utero nicotine” and “improved measures of pulmonary function” in their newborns, according to a study  by Cindy T. McEvoy and others at the Oregon Health and Science University in Portland, published in a recent issue of the Journal of the American Medical Association (JAMA).

Researchers have long known that smoking during pregnancy can harm the respiratory health of newborns. Maternal smoking during pregnancy can interfere with normal lung development, resulting in lifelong increases in asthma risk and other pulmonary complications. The researchers note that “more than 50% of smokers who become pregnant continue to smoke, corresponding to 12% of all pregnancies.” That adds up to a lot of newborns each year who will start off with more wheezing, respiratory infections, and childhood asthma than their counterparts born to non-smoking mothers.

McEvoy and her colleagues wanted to find out whether a daily dose of vitamin C would improve the results of pulmonary function tests in newborns exposed to tobacco in utero.

It did. In an accompanying editorial, Graham L. Hall calls the randomized, double-blind, placebo-controlled clinical trial “well-conceived and executed…. Lung function during the first week of life was statistically significantly better (by approximately 10%) among infants born to mothers randomized to receive Vitamin C compared with infants born to mothers randomized to received placebo.” Moreover, the prevalence of wheezing in the first year was reduced from 40% in the placebo group to 21% in the Vitamin C group.

The decreases in asthma and wheezing in the Vitamin C newborns were documented through the first year of life. 

A 10% reduction does not sound like a lot, but, as Hall writes, “small population-level changes in lung function may lead to significant public health benefits, and the improvements in lung function reported here could be associated with future benefit.”

In their paper, the researchers conclude: “Vitamin C supplementation in pregnant smokers may be an inexpensive and simple approach (with continued smoking cessation counseling) to decrease some of the effects of smoking in pregnancy on newborn pulmonary function and ultimately infant respiratory morbidities, but further study is required.”

Pregnant women should not smoke, and quitting is by far the healthiest option.  As Hall writes: “By preventing her developing fetus and newborn infant from becoming exposed to tobacco smoke, a pregnant woman can do more for the respiratory health and overall health of her child than any amount of vitamin C may be able to accomplish.”

McEvoy C.T.,  Nakia Clay,  Keith Jackson,  Mitzi D. Go,  Patricia Spitale,  Carol Bunten,  Maria Leiva,  David Gonzales,  Julie Hollister-Smith &  Manuel Durand &  (2014). Vitamin C Supplementation for Pregnant Smoking Women and Pulmonary Function in Their Newborn Infants, JAMA, 311 (20) 2074. DOI: http://dx.doi.org/10.1001/jama.2014.5217

Graphics Credit: http://www.quitguide.com/

Smoking and Baby Poop

Telltale metabolites in meconium.

Attention pregnant smokers: You can run, but you can’t hide. A chemical analysis of your baby’s first official poop can establish whether your infant has suffered from prenatal exposure to tobacco smoke. The higher the levels of tobacco metabolites, the more likely the mother was an active smoker.

The authors of a study published in Environmental Health found that nicotine and assorted tobacco metabolites were easily detectable in an infant’s meconium, the black, tar-like substance that comprises the first stools from newborns. In a study of 337 babies, tobacco metabolite concentrations were higher in active smokers than in non-smoking women exposed to second-hand smoke only.

The researchers say the meconium method is not superior to other methods of measurements, but suggest it may be a useful adjunct in estimating “gestational exposure to other environmental toxicants that exhibit more variability during pregnancy, especially non-persistent compounds like bisphenol A and phthalates.”

One striking aspect of the study is that the researchers found nicotine and cotinine—a common nicotine metabolite--in most of the meconium samples analyzed. 80% of the samples contained nicotine. So it is not a question of exposure, it’s a question of the degree of exposure. Should we be concerned about the lower levels of exposure registered from second-hand smoke? Apparently so, since “meconium tobacco smoke metabolites were inversely associated with birth weight,” according to Joe M. Braun and coworkers. Braun suggested that additional biomarkers for tobacco exposure were important, based on his belief that tobacco smoke exposure during pregnancy is under-reported.

This looks like a potentially useful tool for epidemiological studies that enroll women and infants at birth. More studies of this kind are needed, because prenatal tobacco smoke exposure is increasingly implicated in “adverse infant and childhood health outcomes.”

Graphics Credit: http://www.youquittwoquit.com/