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