Prenatal vitamin D supplementation fails to reduce childhood asthma

  • Brustad N & al.
  • JAMA
  • 12 Mar 2019

  • International Clinical Digest
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Takeaway

  • A child does not have a decreased asthma risk at age 6 years if their mother took high vs low doses of prenatal vitamin D.
  • No other effects on lung function seen, either.

Why this matters

  • A link had been hypothesized because of an association identified between low vitamin D levels during pregnancy and asthma in the offspring.

Key results

  • Asthma rates:
    • 8% with high-dose exposure vs 7% with placebo.
    • aOR, 1.21 (95% CI, 0.63-2.32; P=.57).
  • A slight decrease in wheeze at age 3 years in high-dose group disappeared by age 6 years.
  • The authors found no effect of high-dose vitamin D on other outcomes, including lung function, allergic sensitization, rhinitis.

Study design

  • Women were randomly allocated at pregnancy week 24 to 2400 IU/d of vitamin D or placebo+recommended 400 IU/d of vitamin D.
  • Single-center study, Copenhagen, March 2009-November 2010.
  • Children (581) attended 12 clinic visits up to age 6 years.
  • Primary outcome: asthma at age 6 years.
  • Funding: Foundations, government, others.

Limitations

  • Wide confidence intervals suggest reduced power (target enrollment not reached).
  • Study unblinded when children were age 3 years.