• 76 nonsmokers (controls)
• 76 smokers who got 500-milligram (mg) vitamin C supplements for the study
• 83 smokers who got placebo

The study was randomized and double-blind, meaning neither the women nor the staff administering supplements and placebo knew which 89 smokers got supplements and which 90 got placebo. All women were given prenatal vitamins containing 60 mg of vitamin C.

Characteristics of the entire study population included:

• All 15 years or older (average age was 26)
• All singleton pregnancies
• Approximately 22 weeks pregnant upon enrollment in the study (between March 2007 and January 2011)
• 75% were white
• 41% of the women getting supplements smoked 10+ cigarettes a day
• 36% getting placebo smoked 10+ cigarettes a day

Ascorbic acid (vitamin C) levels in the bloodstream were tested at 28 and 30 weeks gestational age to ensure compliance. “Social reasons” were given as the reason why 14.6% of the supplement group and 7.7% of the placebo group dropped out before study’s end.

Pulmonary (lung) function of each newborn was measured when it was 72 hours old. Episodes of wheezing during the first year were noted and pulmonary function tested again at 1 year.

The newborns of smokers assigned the vitamin C supplements fared much better than those of the placebo group:

• At 72 hours, their pulmonary function was healthier
• They experienced fewer wheezing episodes during the first year

At age 1 year, however, there was little difference between the pulmonary function of the children of smokers, regardless of vitamin C supplementation or placebo during pregnancy, indicating a year-long recovery process from smoke exposure in the womb.

The study suggests a solution as simple and inexpensive as vitamin C supplements taken daily during pregnancy might effectively ease the lung damage experienced in utero by the babies of smokers. Vitamin C supplements might also reduce the number of babies who die from respiratory problems caused by nicotine exposure in the womb.

Source: McEvoy, Cindy T, MD, et al. “Vitamin C Supplementation for Pregnant Smoking Women and Pulmonary Function in Their Newborn Infants: A Randomized Clinical Trial.” JAMA. American Medical Association. May 28, 2014. Web. Jun 10, 2014.