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Vitamin D levels during pregnancy did not decrease infant asthma risk

Women who received a high dose of vitamin D while pregnant did not achieve a statistically significant decrease in the risk for having children who developed asthma within the first 3 years of life, according to results from a randomized, double blind, placebo-controlled trial.

“In pregnant women at risk of having a child with asthma, supplementation with 4,400 IU [per day] of vitamin D compared with 400 IU [per day] significantly increased vitamin D levels in the women,” Augusto A. Litonjua, MD, MPH, of the Channing division of network medicine, and department of medicine at Brigham and Women’s Hospital in Boston, and colleagues wrote. “The incidence of asthma and recurrent wheezing in their children at age 3 years was lower by 6.1%, but this did not meet statistical significance; however, the study may have been underpowered. Longer follow-up of the children is ongoing to determine whether the difference is clinically important.”

Litonjua and colleagues evaluated 876 pregnant women aged between 18 to 39 years from the Vitamin D Antenatal Asthma Reduction Trial who were at high risk for having children with asthma. Researchers randomly assigned the women to receive either 4,000 IU daily vitamin D in addition to a prenatal vitamin containing 400 IU of vitamin D (n = 440), or placebo with the prenatal vitamin (n = 436).

The researchers followed 806 of the 810 infants born for the first three years of life.

Two hundred eighteen children from the total cohort developed asthma or recurrent wheeze (HR = 0.8; 95% CI, 0.6-1.0). This included 98 of 405 children (24.3%) in the intervention group (95% CI, 18.7-28.5) and 120 of 401 patients (30.4%) in the control group (95% CI, 25.7-73.1), according to the abstract.

Litonjua and colleagues noted 289 patients (74.9%) in the intervention group had 25-hydroxyvitamin D levels of 30 ng/mL vs. 133 patients (34%) in the control group (difference 40.9%; 95% CI, 34.2-47.5). – by Jeff Craven

Disclosure: Litonjua reports personal fees from Springer Humana Press and UpToDate Inc. Please see the full study for a complete list of all other researchers’ relevant financial disclosures.