Vitamin C supplementation in pregnant women improves offspring airway function

Vitamin C supplementation for pregnant smokers significantly improves airway function and decreases wheeze in children aged 5 years, according to a recent study.

Prenatal exposure to smoke from maternal smoking has been associated with an increased risk of impaired lung development, leading to decreased airway function and increased risk of wheeze and asthma. Over 10% ofindividuals in the United States smoke during pregnancy, causing over 400,000 infants to be exposed to in utero smoke.

Lower airway function in childhood often leads to similarly poor function in adulthood, increasing the risk of respiratory morbidity and chronic obstructive pulmonary disease. Randomized control trials have shown improved airways in children when mothers took vitamin C supplementation during pregnancy, but results in these trials were mixed.

To determine if improved airway function can be achieved early in life and maintained through preschool age, researchers conducted a follow-up investigation to their Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function trial cohort, examining the forced expiratory flow (FEF) of patients aged 5 years.

Participants in the trial included pregnant women aged 15 years and older who had a confirmed single gestation aged 13 to 22 weeks. These individuals also spoke English, had smoked at least 1 in the past week, and were receiving care at clinics near the recruitment sites.

There were 2 groups which participants were randomized into: 1 where they received vitamin C supplementation and 1 where they received a placebo. Data was gathered on participants’ smoking histories and medical adherence, and participants were given brief counseling on smoking cessation.

In the follow-up, FEF measurements for offspring aged 5 years was collected.FEF between 25% and 75% expired volume (FEF25-75), FEF at 50% expired volume (FEF50), and FEF at 75% expired volume (FEF75) were all recorded. Parents and caregivers were also surveyed on the prevalence of wheeze in their children between the child’s fourth and sixth birthdays.

There were 213 children evaluated, with mean ages of 3.1 years in the vitamin C group and 3.2 years in the placebo group. Successful FEF measurements at age 5 were recorded in 90.1% of these children.

Significantly improved FEF25-75 measurements were found in children born to pregnant smokers in the vitamin C supplementation group compared to the placebo group, with a mean difference of 17.2%. Mean FEF50 and FEF75 measurements also improved significantly for children born to women in the vitamin C supplementation group.

The occurrence of wheeze was also significantly lower in children born to pregnant smokers treated with vitamin-C supplementation compared to placebo. Overall, vitamin-C supplementation administered during pregnancy was associated with improved airway function in children born to pregnant smokers.

Reference

McEvoy CT, Shorey-Kendrick LE, Milner K, Harris J, Vuylsteke B, Cunningham M, et al. Effect of vitamin C supplementation for pregnant smokers on offspring airway function and wheeze at age 5 years: follow-up of a randomized clinical trial. JAMA Pediatr. 2023;177(1):16–24. doi:10.1001/jamapediatrics.2022.4401