Vitamin C supplementation improves lung function in fetus exposed to smoke in-utero

The women who are unable to quit smoking during their pregnancy can reduce its (smoking) harmful effects on the lungs of their pre-born infant's by taking vitamin C supplementation, according to a new study.

The study, presented at the ATS (American Thoracic Society) 2018 International Conference finds that the intake of vitamin C supplementation resulted in improved forced expiratory flow (FEF) in their newborns at 3 and 12 months.

"Our findings are of great public health significance to potentially alter the fetal origins of respiratory disease," said Dr. Cynthia McEvoy, Oregon Health & Science University School of Medicine in Portland, Oregon, US. "We used FEFs, as they provide a more direct measurement of actual airway function, and are more predictive of future disease."

For the study, 252 pregnant women (<23 weeks, singleton gestation) who were current cigarette smokers were randomized 1:1 to receive vitamin C (500 mg) daily or placebo through delivery. A total of 243 infants were delivered (n=120 and 123 in the vitamin C and placebo groups, respectively). Median cigarette use was 7 cigarettes/day.

Read Also: Prenatal tobacco smoke exposure worse than postnatal smoke exposure

Key Findings:

• Ascorbic acid levels were higher in the vitamin C group vs the placebo group (60.8 vs 41.6 µmol/L for mid-gestation and 54.6 vs 39.6 µmol/L for late gestation)


• At 3 months, a significant difference in lung function was observed at two intervals between offspring born to women in the vitamin C and placebo groups (436.7 vs 408.5 mL/sec; p=0.02 and 387.4 vs 365.8 mL/sec; p=0.04 for FEF₅₀ and FEF_25-75, respectively).


• The improvement in lung function persisted through 12 months at all intervals (351.6 vs 324.0 mL/sec; p=0.03, 654.5 vs 616.1 mL/sec; p=0.05, and 609.0 vs 567.1 mL/sec; p=0.02 for FEF_75, FEF₅₀, and FEF_25-75, respectively).


• After adjusting for gestational age and other covariates, FEF₇₅ at 3 and 12 months demonstrated a significant effect with vitamin C vs placebo.

McEvoy pointed out that despite active antismoking campaigns and information about nicotine's addictive nature, about 10–12 percent of American women cannot quit smoking while pregnant, pointed out. She further adds that maternal smoking during pregnancy adversely affects fetal lung development, which could lead to lifelong reduced pulmonary function and increased asthma risk in the offspring.

Vitamin C supplementation in this population may improve pulmonary function trajectory of the offspring by blocking some of the effects of in-utero smoke/nicotine on lung structure and function, she said.

A potential mechanism that could elucidate the improved lung function is the interaction between nicotine and nicotinic receptors in developing lungs, noted McEvoy. "This may be a key mediator of the effects of maternal smoking on lung development … [and generate] increased reactive oxygen species. Somehow, vitamin C is blocking that."

For women who cannot quit smoking during pregnancy, these findings show that vitamin C supplementation may be a simple way to 'help babies breathe better', said McEvoy.

Nonetheless, McEvoy underlined that the primary objective remains – which is to get pregnant women to quit smoking despite the observed benefits of vitamin C. "Smoking is the single most preventable cause of perinatal death and increased preterm delivery yet many do not realize that the fetal lung is very sensitive to the effects of in-utero smoke," she said.