Background

We previously reported the results of a trial of prenatal vitamin D supplementation to prevent asthma and recurrent wheeze in young children, which suggested that supplementation provided a protective effect at the age of 3 years. We followed the children through the age of 6 years to determine the course of asthma and recurrent wheeze.

Methods

In this follow-up study, investigators and participants remained unaware of the treatment assignments through the children’s sixth birthday. We aimed to determine whether, when maternal levels of 25-hydroxyvitamin D were taken into account, children born to mothers who had received 4400 IU of vitamin D₃ per day during pregnancy (vitamin D group) would have a lower incidence of asthma and recurrent wheeze at the age of 6 years than would those born to mothers who had received 400 IU of vitamin D₃ per day (control group). Time-to-event methods were used to compare the treatment groups with respect to time to the onset of asthma or recurrent wheeze. Multivariate methods were used to compare longitudinal measures of lung function between the treatment groups.

Results

There was no effect of maternal vitamin D supplementation on asthma and recurrent wheeze in either an intention-to-treat analysis or an analysis with stratification according to the maternal 25-hydroxyvitamin D level during pregnancy. There was no effect of prenatal vitamin D supplementation on most of the prespecified secondary outcomes. We found no effects of prenatal supplementation on spirometric indexes. Although there was a very small effect on airway resistance as measured by impulse oscillometry, this finding was of uncertain significance.

Conclusions

Vitamin D supplementation during the prenatal period alone did not influence the 6-year incidence of asthma and recurrent wheeze among children who were at risk for asthma. (Funded by the National Heart, Lung, and Blood Institute; VDAART ClinicalTrials.gov number, NCT00920621.)

中文翻译：

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产前维生素D减少哮喘试验的六年随访。

背景

我们之前曾报道过一项补充产前维生素D预防幼儿哮喘和反复喘鸣的试验结果，这表明该补充剂对3岁儿童具有保护作用。我们追踪了6岁以下的孩子，以确定哮喘和反复发作的喘息的过程。

方法

在这项后续研究中，研究人员和参与者一直不知道孩子六岁生日时的治疗任务。我们旨在确定，考虑到母亲的25-羟基维生素D水平，怀孕期间每天接受4400 IU维生素D _3的母亲所生的孩子（维生素D组）是否会降低哮喘的发病率和复发率与每天接受400 IU维生素D _3的母亲所生的婴儿（对照组）相比，他们在6岁时喘息。事件发生时间的方法用于比较治疗组与哮喘或复发性喘息发作时间的关系。使用多变量方法比较治疗组之间的肺功能纵向测量值。

结果

根据怀孕期间孕妇的母体25-羟基维生素D水平，在意向性治疗分析或分层分析中，母体维生素D补充剂对哮喘和复发性喘息均无影响。产前补充维生素D对大多数预定的次要结局没有影响。我们发现产前补充对肺活量指数没有影响。尽管通过脉冲示波法测量对气道阻力的影响很小，但这一发现尚不确定。

结论

仅在产前补充维生素D并不会影响有哮喘风险的儿童的6年哮喘发病率和反复喘息。（由美国国家心脏，肺和血液研究所资助； VDAART ClinicalTrials.gov编号，NCT00920621。）