Vitamin C supplements during pregnancy nullify harms of smoking on foetus

USA: Smoking during pregnancy is reportedly known to have an adverse impact on fetus health. A new study suggests that regular intake of vitamin C supplements by pregnant smokers may reduce the harm inflicted by smoking on fetus lungs after birth.

Results of this randomized, controlled trial are published in the American Journal of Respiratory and Critical Care Medicine.

Cindy T McEvoy, Oregon Health & Science University, Pediatrics, Portland, Oregon, US, and colleagues conducted the study to determine if regular vitamin C supplementation by pregnant smokers improved forced expiratory flows (FEFs) in their infants at 3 months of age compared to placebo, and to investigate the association of the α5 nicotinic acetylcholine receptor.

FEFs measure how fast air can be exhaled from the lung and are an important measure of lung function because they can detect airway obstruction.

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The authors used passive methods to measure lung function, and the authors note that FEFs provide a more direct assessment of airway function and are similar to methods used to diagnose lung disease in adults and older children.

For the study, 251 pregnant women who smoked were randomly assigned at 13 to 23 weeks of gestation to either receive vitamin C (125 women) or a placebo (126 women). Smoking was defined as having had one or more cigarettes in the last week. All participants received smoking cessation counseling throughout the study, and about 10 percent of the women quit smoking during the study.

Based on the findings, the authors report that at three months of age, the infants whose mothers took 500 mg of vitamin C in addition to their prenatal vitamin had significantly better FEFs.

The researchers also discovered an association between the infant FEFs and a genetic variant some of the mothers possessed that appeared to amplify the negative impact of nicotine on the babies before they were born. Other studies have linked this genetic factor, specifically for the α5 nicotinic acetylcholine receptor, to increased risk of lung cancer and obstructive lung disease.

"Smoking during pregnancy reflects the highly addictive nature of nicotine that disproportionately affects the most vulnerable populations. Finding a way to help infants exposed to smoking and nicotine in utero recognizes the unique dangers posed by a highly advertised, addictive product and the lifetime effects on offspring who did not choose to be exposed," said Dr. McEvoy.

The study results support the hypothesis that oxidative stress caused by cigarette smoking reduces the amount of ascorbic acid, a component of vitamin C, available to the body. At the time they enrolled in the study, the women had lower levels of ascorbic acid than have been reported among women who do not smoke.

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Those levels rose in study participants who received vitamin C to become comparable to women who do not smoke.

A relatively low dosage of vitamin C may present "a safe and inexpensive intervention that has the potential to help lung health of millions of infants worldwide," Dr. McEvoy said summing up the findings of the current study.

"Although vitamin C supplementation may protect to some extent the lungs of babies born to mothers who smoke during pregnancy, those children will still be at greater risk for obesity, behavioral disorders, and other serious health issues," she said.

For further reference log on to https://doi.org/10.1164/rccm.201805-1011OC