Supplementary Material for: Maternal dietary vitamin D intake during pregnancy is associated with allergic disease symptoms in children at 3 years old: the Japan Environment and Children’s Study

Introduction: Vitamin D plays an important role in the immune system, and postnatal vitamin D insufficiency is one of the risk factors for the development of allergic disease. However, the effects of women’s vitamin D intake during pregnancy on the prevalence of allergic disease in their children remain controversial. Methods: From the Japan Environment and Children’s Study, an ongoing nationwide birth cohort study, we obtained information on maternal dietary vitamin D intake determined using a food frequency questionnaire and parent-reported allergic disease symptoms based on the ISAAC questionnaire in children at 3 years of age. Results: From the full dataset of 103,060 pregnancies, we analyzed complete data for 73,309 mother–child pairs. The prevalence of current wheeze, current rhinitis, current rhino-conjunctivitis, current eczema, ever asthma, ever pollinosis, and ever atopic dermatitis in the children was 17.2%, 29.7%, 3.8%, 15.2%, 9.6%, 3.7%, and 11.0%, respectively. The ORs for current rhinitis were significantly lower in the 3rd, 4th, and 5th quintiles than in the 1st quintile after adjustment for various covariates and showed a linear association. The ORs for ever pollinosis were significantly lower in the 2nd, 3rd, and 4th quintiles than in the 1st quintile, showing a U-shaped curve. There was no clear association between mothers’ dietary vitamin D intake and symptoms of asthma or atopic dermatitis in their 3-year-old children. Conclusion: Maternal dietary vitamin D intake during pregnancy is associated with the ORs for nasal allergies in children at the age of 3 years. Further studies are warranted to evaluate the appropriate intake dose of vitamin D for pregnant women to prevent the development of nasal allergies in their children.

引言：维生素D（Vitamin D）对免疫系统具有重要调控作用，产后维生素D摄入不足是过敏性疾病发生的危险因素之一。然而，女性妊娠期膳食维生素D摄入对子代过敏性疾病患病率的影响仍存在争议。
方法：本研究依托正在开展的全国性出生队列研究——日本环境与儿童研究（Japan Environment and Children’s Study），通过食物频率问卷（food frequency questionnaire）收集母亲膳食维生素D摄入信息，并采用ISAAC问卷（International Study of Asthma and Allergies in Childhood questionnaire）由家长报告子代3岁时的过敏性疾病症状。
结果：本研究初始完整数据集涵盖103060例妊娠案例，最终纳入73309对母婴的完整数据进行分析。子代现患喘息、现患鼻炎、现患鼻结膜炎、现患湿疹、曾诊哮喘、曾诊花粉症及曾诊特应性皮炎的患病率分别为17.2%、29.7%、3.8%、15.2%、9.6%、3.7%及11.0%。经多协变量调整后，第3、4、5五分位组子代现患鼻炎的比值比（Odds Ratio，OR）显著低于第1五分位组，且呈现线性关联；第2、3、4五分位组子代曾诊花粉症的OR显著低于第1五分位组，呈现U型曲线关联。母亲妊娠期膳食维生素D摄入与3岁子代哮喘或特应性皮炎症状无明确关联。
结论：母亲妊娠期膳食维生素D摄入与3岁子代鼻部过敏性疾病的OR值存在关联。未来需开展进一步研究，以明确妊娠期女性预防子代鼻部过敏性疾病的适宜维生素D摄入量。