BACKGROUND AND PURPOSE:

• Daily vitamin C supplementation in pregnant smokers has been shown to increase newborn pulmonary function and infant forced expiratory flows (FEFs) at 3 months
• McEvoy et al. (European Respiratory Journal, 2020) assessed whether vitamin C supplementation in pregnant smokers was associated with improved airway function in their infants through 12 months of age

METHODS:

• Secondary outcome of a randomized, double-blind, placebo-controlled trial
• Participants
  • Pregnant smokers between 13 and 23 weeks of gestation
• Interventions
  • Vitamin C: 125 to 500 mg/day
  • Placebo
• Study design
  • Participants were also provided with smoking cessation counseling
  • FEFs performed at 3 and 12 months of age

RESULTS:

• 222 infants examined at 3 months | 202 infants examine at 12 months
• While overall characteristics were similar between groups, women in the Vitamin C treatment group had significantly higher fasting ascorbic acid levels at mid (p<0.001) and late gestation (p<0.001)
• Compared to placebo, infants born to mothers in the vitamin C group had significantly increased FEFs over the first year of life
• Overall increased flows between 3 and 12 months
  • FEF75: 40.2 mL/sec (95% CI, 6.6 to 73.8; p = 0.025) | 16.1% effective increase
  • FEF50: 58.3 mL/sec (95% CI, 10.9 to 105.8; p = 0.0081) | 11.6% effective increase
  • FEF25 to 75: 55.1 mL/sec (95% CI, 9.7 to 100.5; p = 0.013) | 12% effective increase

CONCLUSION:

• Infants born to smokers who took a vitamin C supplement every day had small but significant increased airway function at 3 and 12 months of age, compared to infants born to smokers who did not supplement
• The study was underpowered to assess clinical outcomes such as wheezing
• The research team will be continuing the study to 5 years of age
• The authors state that while the main goal should always be smoking cessation

This study demonstrates that the safe, inexpensive and simple intervention of vitamin C supplementation can persistently improve the airway function of infants exposed to in utero smoke

Learn More – Primary Sources:

Vitamin C to Pregnant Smokers Persistently Improves Infant Airway Function to 12 Months of Age: A Randomised Trial

Related ObG Topics:

Does Smoking During Pregnancy Affect the Fetal Immune System?

Increasing the Folic Acid Dose for Women Who Smoke: Does it Reduce the Risk of Fetal Growth Restriction?

Safe Passage Study: Prenatal Alcohol Exposure and Cognitive Abilities at 4 years of Age