Researchers at Oregon Health & Science University found that supplementing vitamin C to pregnant women who were unable to quit smoking significantly improved the airway function and respiratory health of their offspring at age 5.
While previous studies have shown that vitamin C improves airway function in infants, this is the first study to demonstrate whether the improvement in airway function can be sustained into preschool age.
The study, published this week in JAMA Pediatrics.
Despite anti-smoking efforts and a steady decline in smoking among the elderly population over the past decade, the addictive properties of tobacco products can make quitting smoking incredibly challenging for many people. Approximately 10% of American women continue to smoke during pregnancy, resulting in approximately 400,000 babies exposed to smoke in the womb or in utero each year.
“By now we know how addictive tobacco products can be. For many people, it may take many attempts over a long period of time to quit smoking if they are successful,” said Cindy McEvoy, Ph.D, professor of pediatrics at the OHSU School of Medicine and lead investigator of the study. “It’s important to have a way to protect a baby’s developing lungs, even if their parent is struggling to quit smoking.” These findings have identified an affordable, effective way to ensure optimal respiratory health outcomes both in utero and throughout a child’s young life.
Secondhand smoke exposure from maternal smoking during pregnancy can be dangerous to the developing baby and is associated with poor health outcomes, including impaired fetal lung development, reduced airway function, and increased risk of wheezing and asthma. In addition, reduced airway growth early in life causes an increased risk of serious conditions throughout life, such as chronic obstructive pulmonary disease, now the third leading cause of death worldwide.
For this study, researchers recruited pregnant women from three sites: OHSU, PeaceHealth Southwest Washington Medical Center, and Indiana University. Female participants were enrolled in a double-blind, randomized controlled trial to receive vitamin C (500 mg/day) or placebo.
Statistical analyzes showed that the effect of vitamin C supplementation in pregnant women who smoked before 23 weeks of gestation consistently resulted in significantly better airway function in their offspring at 5 years of age.
While the findings may improve the health of many children who face in utero smoke exposure, these findings may have even broader implications: The findings could potentially lead to a better understanding and treatment of the health effects of other exposures of smoke, including indoor and outdoor air pollution, vaping and forest fires.
McEvoy also notes that further research is needed to understand the mechanisms of improvement, as well as to determine whether improved respiratory outcomes will last throughout a child’s life. Researchers are also interested in learning more about the optimal timing of vitamin C treatment and the steps needed to make this therapy part of standard medical treatment.
This work was supported by the following grants: NHLBI (R01 HL105447 and 406 R01 HL 105460) with co-funding from the Office of Dietary Supplements (ODS) and by 407 P51 OD011092565 and NIH UH3 OD023288. Additional support from the Oregon 408 Clinical Translational Research Institute funded by the National Center for the Advancement of 409 Translational Sciences (UL1TR000128).