Vitamin C May Reduce Harm of Smoking During Pregnancy

Women who are unable to quit smoking during their pregnancy may reduce the harm smoking does to their baby's lungs by taking vitamin C, according to a new study.

Researchers at Oregon Health & Science University (OHSU; Portland, USA), the Indiana University School of Medicine (Indianapolis, USA), and other institutions conducted a randomized, double-blind, placebo-controlled trial to evaluate pulmonary function at three months of age in infants delivered to pregnant smokers, in order to see if Vitamin C could decrease the effects of smoking during pregnancy on infant lung function. To do so, they measured force expiratory flows (FEFs) at three and 12 months of babies born to 252 mothers who smoked. On average, the mothers in both arms of the study who could not quit smoked seven cigarettes a day.

The mothers who smoked were randomized between 13 and 23 weeks gestation to either 500 mg of supplemental vitamin C every day or a placebo, in addition to the same prenatal vitamin. FEFs were measured at three intervals, and defined by the percentage of air remaining in the lung during forced exhalation: FEF75, FEF25-75, and FEF50. The results showed a statistically significant difference in lung function between the babies born to the two groups at the FEF25-75 and FEF50 intervals at three months.

And at 12 months, a statistically significant difference in lung function was identified between the two groups at all three intervals. The study also found that babies whose mothers took vitamin C were less likely to develop wheeze at one year. The study did not find a significant difference between the two groups of babies in gestational age at delivery, delivery mode, incidence of prematurity, or birth weight. The study was presented at the annual American Thoracic Society (ATS) conference, held during May 2018, in San Diego (CA, USA).

“We performed FEFs in this study because they provide a more direct measurement of actual air way function, and are more predictive of future disease,” said lead author professor of pediatrics Cynthia McEvoy, MD, of the OHSU Doernbecher Children's Hospital. “Getting women to quit smoking during pregnancy has to be priority one. For those roughly 50% of pregnant smokers who will not, or cannot quit despite all efforts, quit smoking, vitamin C supplementation may be a simple and safe way to help their babies breathe better.”

Smoking during pregnancy is the largest preventable cause of childhood respiratory illness, including decreased pulmonary function, wheezing, and asthma. Despite strong anti-smoking efforts, at least 12% of American women cannot quit smoking when pregnant, resulting in over 450,000 smoke-exposed infants born yearly. Preliminary data suggests that the mechanism underlying vitamin C’s prevention of some of the effects of maternal smoking on offspring pulmonary health involves the prevention of epigenetic changes induced by maternal smoking.

Related Links:
Oregon Health & Science University
Indiana University School of Medicine