Asthma prevention study suggests vitamin D supplementation in pregnant women might affect specific immune responses in offspring

WHAT: Providing extra vitamin D to women during pregnancy raised their vitamin D levels without changing recurrent wheezing rates in their offspring by age 3 years, National Institutes of Health-supported research found. However, in these children, who are at high risk for developing asthma, blood tests showed lower levels of specific antibodies related to allergy development, if their mothers took extra vitamin D, according to results appearing in the Journal of the American Medical Association.

While the study showed a small decrease in the rates of recurrent wheezing in children up to the age of 3 years, the difference was not considered to be statistically significant. The NIH’s National Heart, Lung, and Blood Institute (NHLBI) is continuing to fund the study to follow these children up to the age of 6 years to see to see how many develop asthma, and to determine possible effects of vitamin D on lung function.

The Vitamin D Antenatal Asthma Reduction Trial (VDAART) looked at 881 pregnant women considered to be at high risk for having children who develop asthma during childhood. Half of the participants received a supplement containing 4,000 international units (IUs) of vitamin D and the other half was given a placebo pill that contained no active ingredients.  All participants were also given a standard prenatal vitamin that contained 400 IUs of vitamin D. The study found that 75 percent of women taking supplemental vitamin D were at or above their target range versus 34 percent of women in the other group.

Vitamin D deficiency is considered a global problem, and pregnant women are at increased risk for such a deficiency. One national study found nearly 70 percent of pregnant women had insufficient levels of vitamin D. Researchers believe the vitamin may play a role in the development of the pulmonary and the immune system.

During the study, 806 children were born, and 218 of these developed a noisy pattern of breathing, called wheezing, which is associated with asthma. From the group of women receiving supplemental vitamin D, 98 children were found to wheeze, compared to 120 children born to women in the group that did not receive additional vitamin D.

VDAART is the first trial, in the United States, to look at interventions in pregnant women as a way to prevent asthma in their children. Asthma is considered one of the most common childhood chronic diseases, with an estimated one in 11 U.S. children having the condition. The study (Clinical Trial number NCT00920621) is led by researchers at the Brigham and Women’s Hospital, Boston, Mass. The study was funded through NHLBI grant number R01HL108818.

WHO:  James Kiley, Ph.D., director, Division of Lung Diseases, NHLBI, NIH, is available to comment on the findings and implications of this research.

CONTACT: For more information or to schedule an interview, please contact the NHLBI Office of Science Policy, Engagement, Education, and Communications at 301-496-4236 or nhlbi_news@nhlbi.nih.gov (link sends e-mail).