Reduced primary care respiratory infection visits following pregnancy and infancy vitamin D supplementation: a randomised controlled trial

AimTo determine whether vitamin D supplementation reduces primary care visits for acute respiratory infection (ARI). MethodsA randomised, double-blind, placebo-controlled trial was conducted in New Zealand and powered to determine the vitamin D dose needed to achieve normal vitamin D status during infancy. Healthy pregnant women, from 27weeks' gestation to birth, and their infants, from birth to age 6months, were assigned to placebo or one of the two dosages of daily oral vitamin D-3. Woman/infant pairs were randomised to placebo/placebo, 1000IU/400IU or 2000IU/800IU. For this ad hoc analysis, the primary care records of enrolled children were audited to age 18months. ResultsTwo hundred and sixty pregnant women were randomised to placebo (n=87), lower-dose (n=87) or higher-dose (n=86) vitamin D-3. In comparison with the placebo group (99%), the proportion of children making any ARI visits was smaller in the higher-dose (87%, p=0.004), but not the lower-dose vitamin D-3 group (95%, p=0.17). The median number of ARI visits/child was less in the higher-dose vitamin D-3 group from age 6-18 months (placebo 4, lower dose 3, higher dose 2.5; p=0.048 for higher-dose vitamin D-3 vs. placebo). ConclusionVitamin D-3 supplementation during pregnancy and infancy reduces primary care visits for ARI during early childhood.