Does Prenatal Supplementation With Vitamin D Affect Childhood Asthma?

Augusto A. Litonjua, MD, MPH Associate Professor Channing Division of Network Medicine and Division of Pulmonary and Critical Care Medicine Department of Medicine Brigham and Women's Hospital Harvard Medical School Boston, MA 02115 USA

Dr. Augusto Litonjua

MedicalResearch.com Interview with:
Augusto A. Litonjua, MD, MPH
Associate Professor
Channing Division of Network Medicine
and Division of Pulmonary and Critical Care Medicine
Department of Medicine
Brigham and Women’s Hospital
Harvard Medical School
Boston, MA 02115 USA 

Medical Research: What is the background for this study? What are the main findings?

Response: Vitamin D deficiency has been hypothesized to contribute to the asthma and allergy epidemic.  Vitamin D has been shown to affect lung development in utero. However, observational studies have shown mixed results when studying asthma development in young children. Since most asthma cases start out as wheezing illnesses in very young children, we hypothesized that vitamin D supplementation in pregnant mothers might prevent the development of asthma and wheezing illnesses in their offspring.  We randomly assigned 881 pregnant women at 10 to 18 weeks’ gestation and at high risk of having children with asthma to receive daily 4,000 IU vitamin D plus a prenatal vitamin containing 400 IU vitamin D (n = 440), or a placebo plus a prenatal vitamin containing 400 IU vitamin D (n = 436). Eight hundred ten infants were born during the study period, and 806 were included in the analyses for the 3-year outcomes. The children born to mothers in the 4,400 IU group had a 20% reduction in the development of asthma or recurrent wheeze compared to the children born to mothers in the 400 IU group (24% vs 30%, respectively; an absolute reduction of 6%).  However, this reduction did not reach statistical significance (p=0.051).

Medical Research: What should clinicians and patients take away from your report?

Response: While these findings do not show conclusively that vitamin D supplementation in pregnancy prevents the development of asthma or recurrent wheeze in young children, the results are encouraging. At the least, steps should be taken to prevent vitamin D deficiency in pregnancy.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Future studies will need to take account of the limitations that we identified in our study. First, a larger study will need to be done. Next, because there were fewer women who attained the target level of vitamin D by late in their pregnancy, consideration for individualized dosing may be necessary, based on the baseline level of circulating vitamin D. Thirdly, because we did not supplement the offspring, the effect of vitamin D may not have been sustained after birth, therefore, future studies will need to incorporate post-natal supplementation.

MedicalResearch.com: Is there anything else you would like to add?

Response: We are continuing to follow the children in the study up to age 6 years, where we will see if prenatal vitamin D supplementation had an effect on lung function.

Citation:

Dr. Augusto A. Litonjua (2015). Does Prenatal Supplementation With Vitamin D Affect Childhood Asthma? MedicalResearch.com

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