Women were randomised to receive either daily 4000 IU vitamin D plus a prenatal vitamin containing 400 IU vitamin D, or placebo in combination with a prenatal vitamin containing 400 IU vitamin D.
An editorial comments on this study as well as a related study which looked at the occurrence of persistent wheeze in the first 3 years of life. The authors suggest that given the lack of any major unwanted effects observed in either of these trials, prescribing a higher than recommended vitamin D–containing supplement during pregnancy to mothers who are at high risk of having children with asthma (ie, with a history of asthma, eczema, or allergic rhinitis) seems to be a reasonable strategy, especially if the pregnant woman has evidence of vitamin D deficiency.
Current NICE guidance on “Vitamin D: increasing supplement use in at-risk groups” recommends “Healthy Start” vitamin supplementation in pregnant women, which contains 400IU of vitamin D.